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Chapter 13

Fundamental Concepts of Algebra — Exercise 13(F)

Class - 7 Concise Mathematics Selina



Exercise 13(F)

Question 1

Enclose the given term in bracket as required:

x−y−z=xx - y - z = x − (.......................)

Answer

x−y−z=x−(y+z)x - y - z = x - (\bm{y + z})

Question 2

Enclose the given term in bracket as required:

x2−xy2−2xy−y2=x2x^2 - xy^2 - 2xy - y^2 = x^2 − (.......................)

Answer

x2−xy2−2xy−y2=x2−(xy2+2xy+y2)x^2 - xy^2 - 2xy - y^2 = x^2 - (\bm{xy^2 + 2xy + y^2})

Question 3

Enclose the given term in bracket as required:

4a−9+2b−6=4a4a - 9 + 2b - 6 = 4a − (.......................)

Answer

4a−9+2b−6=4a−(9−2b+6)4a - 9 + 2b - 6 = 4a - (\bm{9 - 2b + 6})

Question 4

Enclose the given term in bracket as required:

x2−y2+z2+3x−2y=x2x^2 - y^2 + z^2 + 3x - 2y = x^2 − (.......................)

Answer

x2−y2+z2+3x−2y=x2−(y2−z2−3x+2y)x^2 - y^2 + z^2 + 3x - 2y = x^2 - (\bm{y^2 - z^2 - 3x + 2y})

Question 5

Enclose the given term in bracket as required:

−2a2+4ab−6a2b2+8ab2=−2a-2a^2 + 4ab - 6a^2b^2 + 8ab^2 = -2a (.......................)

Answer

−2a2+4ab−6a2b2+8ab2=−2a(a−2b+3ab2−4b2)-2a^2 + 4ab - 6a^2b^2 + 8ab^2 = -2a(\bm{a - 2b + 3ab^2 - 4b^2})

Question 6

Simplify:

2x−(x+2y−z)2x - (x + 2y - z)

Answer

Solving,

⇒2x−(x+2y−z)⇒2x−x−2y+z⇒x−2y+z\Rightarrow 2x - (x + 2y - z)\\[1em] \Rightarrow 2x - x - 2y + z\\[1em] \Rightarrow x - 2y + z

Hence, 2x−(x+2y−z)=x−2y+z\bm{2x - (x + 2y - z) = x - 2y + z}.

Question 7

Simplify:

p+q−(p−q)+(2p−3q)p + q - (p - q) + (2p - 3q)

Answer

Solving,

⇒p+q−(p−q)+(2p−3q)⇒p+q−p+q+2p−3q⇒(1−1+2)p+(1+1−3)q⇒2p−q\Rightarrow p + q - (p - q) + (2p - 3q)\\[1em] \Rightarrow p + q - p + q + 2p - 3q\\[1em] \Rightarrow (1 - 1 + 2)p + (1 + 1 - 3)q\\[1em] \Rightarrow 2p - q

Hence, p+q−(p−q)+(2p−3q)=2p−q\bm{p + q - (p - q) + (2p - 3q) = 2p - q}.

Question 8

Simplify:

9x−(−4x+5)9x - (- 4x + 5)

Answer

Solving,

⇒9x−(−4x+5)⇒9x+4x−5⇒13x−5\Rightarrow 9x - (-4x + 5)\\[1em] \Rightarrow 9x + 4x - 5\\[1em] \Rightarrow 13x - 5

Hence, 9x−(−4x+5)=13x−5\bm{9x - (-4x + 5) = 13x - 5}.

Question 9

Simplify:

6a−(−5a−8b)+(3a+b)6a - (- 5a - 8b) + (3a + b)

Answer

Solving,

⇒6a−(−5a−8b)+(3a+b)⇒6a+5a+8b+3a+b⇒(6+5+3)a+(8+1)b⇒14a+9b\Rightarrow 6a - (-5a - 8b) + (3a + b)\\[1em] \Rightarrow 6a + 5a + 8b + 3a + b\\[1em] \Rightarrow (6 + 5 + 3)a + (8 + 1)b\\[1em] \Rightarrow 14a + 9b

Hence, 6a−(−5a−8b)+(3a+b)=14a+9b\bm{6a - (-5a - 8b) + (3a + b) = 14a + 9b}.

Question 10

Simplify:

(p−2q)−(3q−r)(p - 2q) - (3q - r)

Answer

Solving,

⇒(p−2q)−(3q−r)⇒p−2q−3q+r⇒p−5q+r\Rightarrow (p - 2q) - (3q - r)\\[1em] \Rightarrow p - 2q - 3q + r\\[1em] \Rightarrow p - 5q + r

Hence, (p−2q)−(3q−r)=p−5q+r\bm{(p - 2q) - (3q - r) = p - 5q + r}.

Question 11

Simplify:

9a(2b−3a+7c)9a (2b - 3a + 7c)

Answer

Solving,

⇒9a(2b−3a+7c)⇒9a×2b−9a×3a+9a×7c⇒18ab−27a2+63ac\Rightarrow 9a(2b - 3a + 7c)\\[1em] \Rightarrow 9a \times 2b - 9a \times 3a + 9a \times 7c\\[1em] \Rightarrow 18ab - 27a^2 + 63ac

Hence, 9a(2b−3a+7c)=18ab−27a2+63ac\bm{9a(2b - 3a + 7c) = 18ab - 27a^2 + 63ac}.

Question 12

Simplify:

−5m(−2m+3n−7p)-5m (- 2m + 3n - 7p)

Answer

Solving,

⇒−5m(−2m+3n−7p)⇒−5m×(−2m)−5m×3n−5m×(−7p)⇒10m2−15mn+35mp\Rightarrow -5m(-2m + 3n - 7p)\\[1em] \Rightarrow -5m \times (-2m) - 5m \times 3n - 5m \times (-7p)\\[1em] \Rightarrow 10m^2 - 15mn + 35mp

Hence, −5m(−2m+3n−7p)=10m2−15mn+35mp\bm{-5m(-2m + 3n - 7p) = 10m^2 - 15mn + 35mp}.

Question 13

Simplify:

−2x(x+y)+x2-2x (x + y) + x^2

Answer

Solving,

⇒−2x(x+y)+x2⇒−2x2−2xy+x2⇒−x2−2xy\Rightarrow -2x(x + y) + x^2\\[1em] \Rightarrow -2x^2 - 2xy + x^2\\[1em] \Rightarrow -x^2 - 2xy

Hence, −2x(x+y)+x2=−x2−2xy\bm{-2x(x + y) + x^2 = -x^2 - 2xy}.

Question 14

Simplify:

b(2b−1b)−2b(b−1b)b\left(2b - \dfrac{1}{b}\right) - 2b\left(b - \dfrac{1}{b}\right)

Answer

Solving,

⇒b(2b−1b)−2b(b−1b)⇒2b2−1−2b2+2⇒1\Rightarrow b\left(2b - \dfrac{1}{b}\right) - 2b\left(b - \dfrac{1}{b}\right)\\[1em] \Rightarrow 2b^2 - 1 - 2b^2 + 2\\[1em] \Rightarrow 1

Hence, b(2b−1b)−2b(b−1b)=1\bm{b\left(2b - \dfrac{1}{b}\right) - 2b\left(b - \dfrac{1}{b}\right) = 1}.

Question 15

Simplify:

8(2a+3b−c)−10(a+2b+3c)8 (2a + 3b - c) - 10 (a + 2b + 3c)

Answer

Solving,

⇒8(2a+3b−c)−10(a+2b+3c)⇒16a+24b−8c−10a−20b−30c⇒(16−10)a+(24−20)b+(−8−30)c⇒6a+4b−38c\Rightarrow 8(2a + 3b - c) - 10(a + 2b + 3c)\\[1em] \Rightarrow 16a + 24b - 8c - 10a - 20b - 30c\\[1em] \Rightarrow (16 - 10)a + (24 - 20)b + (-8 - 30)c\\[1em] \Rightarrow 6a + 4b - 38c

Hence, 8(2a+3b−c)−10(a+2b+3c)=6a+4b−38c\bm{8(2a + 3b - c) - 10(a + 2b + 3c) = 6a + 4b - 38c}.

Question 16

Simplify:

a(a+1a)−b(b−1b)−c(c+1c)a\left(a + \dfrac{1}{a}\right) - b\left(b - \dfrac{1}{b}\right) - c\left(c + \dfrac{1}{c}\right)

Answer

Solving,

⇒a(a+1a)−b(b−1b)−c(c+1c)⇒(a2+1)−(b2−1)−(c2+1)⇒a2+1−b2+1−c2−1⇒a2−b2−c2+1\Rightarrow a\left(a + \dfrac{1}{a}\right) - b\left(b - \dfrac{1}{b}\right) - c\left(c + \dfrac{1}{c}\right)\\[1em] \Rightarrow (a^2 + 1) - (b^2 - 1) - (c^2 + 1)\\[1em] \Rightarrow a^2 + 1 - b^2 + 1 - c^2 - 1\\[1em] \Rightarrow a^2 - b^2 - c^2 + 1

Hence, a(a+1a)−b(b−1b)−c(c+1c)=a2−b2−c2+1\bm{a\left(a + \dfrac{1}{a}\right) - b\left(b - \dfrac{1}{b}\right) - c\left(c + \dfrac{1}{c}\right) = a^2 - b^2 - c^2 + 1}.

Question 17

Simplify:

5x(2x+3y)−2x(x−9y)5x (2x + 3y) - 2x (x - 9y)

Answer

Solving,

⇒5x(2x+3y)−2x(x−9y)⇒10x2+15xy−2x2+18xy⇒8x2+33xy\Rightarrow 5x(2x + 3y) - 2x(x - 9y)\\[1em] \Rightarrow 10x^2 + 15xy - 2x^2 + 18xy\\[1em] \Rightarrow 8x^2 + 33xy

Hence, 5x(2x+3y)−2x(x−9y)=8x2+33xy\bm{5x(2x + 3y) - 2x(x - 9y) = 8x^2 + 33xy}.

Question 18

Simplify:

a+(b+c−d)a + (b + c - d)

Answer

Solving,

⇒a+(b+c−d)⇒a+b+c−d\Rightarrow a + (b + c - d)\\[1em] \Rightarrow a + b + c - d

Hence, a+(b+c−d)=a+b+c−d\bm{a + (b + c - d) = a + b + c - d}.

Question 19

Simplify:

5−8x−(6−x)5 - 8x - (6 - x)

Answer

Solving,

⇒5−8x−(6−x)⇒5−8x−6+x⇒−1−7x\Rightarrow 5 - 8x - (6 - x)\\[1em] \Rightarrow 5 - 8x - 6 + x\\[1em] \Rightarrow -1 - 7x

Hence, 5−8x−(6−x)=−1−7x\bm{5 - 8x - (6 - x) = -1 - 7x}.

Question 20

Simplify:

2a+(b−a−b‾)2a + (b - \overline{a - b})

Answer

Solving,

⇒2a+(b−a−b‾)⇒2a+(b−a+b)⇒2a+b−a+b⇒a+2b\Rightarrow 2a + (b - \overline{a - b})\\[1em] \Rightarrow 2a + (b - a + b)\\[1em] \Rightarrow 2a + b - a + b\\[1em] \Rightarrow a + 2b

Hence, 2a+(b−a−b‾)=a+2b\bm{2a + (b - \overline{a - b}) = a + 2b}.

Question 21

Simplify:

3x+[4x−(6x−3)]3x + [4x - (6x - 3)]

Answer

Solving,

⇒3x+[4x−(6x−3)]⇒3x+[4x−6x+3]⇒3x+4x−6x+3⇒x+3\Rightarrow 3x + [4x - (6x - 3)]\\[1em] \Rightarrow 3x + [4x - 6x + 3] \\[1em] \Rightarrow 3x + 4x - 6x + 3 \\[1em] \Rightarrow x + 3

Hence, 3x+[4x−(6x−3)]=x+3\bm{3x + [4x - (6x - 3)] = x + 3}.

Question 22

Simplify:

5b−{6a+(8−b−a)}5b - \big\lbrace 6a + (8 - b - a)\big\rbrace

Answer

Solving,

⇒5b−{6a+(8−b−a)}⇒5b−{6a+8−b−a}⇒5b−{5a+8−b}⇒5b−5a−8+b⇒6b−5a−8\Rightarrow 5b - \big\lbrace 6a + (8 - b - a)\big\rbrace\\[1em] \Rightarrow 5b - \big\lbrace 6a + 8 - b - a\big\rbrace \\[1em] \Rightarrow 5b - \big\lbrace 5a + 8 - b\big\rbrace\\[1em] \Rightarrow 5b - 5a - 8 + b \\[1em] \Rightarrow 6b - 5a - 8

Hence, 5b−{6a+(8−b−a)}=6b−5a−8\bm{5b - \big\lbrace6a + (8 - b - a)\big\rbrace = 6b - 5a - 8}.

Question 23

Simplify:

2x−[5y−(3x−y)+x]2x - [5y - (3x - y) + x]

Answer

Solving,

⇒2x−[5y−(3x−y)+x]⇒2x−[5y−3x+y+x]⇒2x−[6y−2x]⇒2x−6y+2x⇒4x−6y\Rightarrow 2x - [5y - (3x - y) + x]\\[1em] \Rightarrow 2x - [5y - 3x + y + x] \\[1em] \Rightarrow 2x - [6y - 2x]\\[1em] \Rightarrow 2x - 6y + 2x \\[1em] \Rightarrow 4x - 6y

Hence, 2x−[5y−(3x−y)+x]=4x−6y\bm{2x - [5y - (3x - y) + x] = 4x - 6y}.

Question 24

Simplify:

6a−3(a+b−2)6a - 3 (a + b - 2)

Answer

Solving,

⇒6a−3(a+b−2)⇒6a−3a−3b+6⇒3a−3b+6\Rightarrow 6a - 3(a + b - 2)\\[1em] \Rightarrow 6a - 3a - 3b + 6\\[1em] \Rightarrow 3a - 3b + 6

Hence, 6a−3(a+b−2)=3a−3b+6\bm{6a - 3(a + b - 2) = 3a - 3b + 6}.

Question 25

Simplify:

8[m+2n−p−7(2m−n+3p)]8[m + 2n - p - 7(2m - n + 3p)]

Answer

Solving,

⇒8[m+2n−p−7(2m−n+3p)]⇒8[m+2n−p−14m+7n−21p]⇒8[(1−14)m+(2+7)n+(−1−21)p]⇒8[−13m+9n−22p]⇒−104m+72n−176p\Rightarrow 8[m + 2n - p - 7(2m - n + 3p)]\\[1em] \Rightarrow 8[m + 2n - p - 14m + 7n - 21p] \\[1em] \Rightarrow 8[(1 - 14)m + (2 + 7)n + (-1 - 21)p]\\[1em] \Rightarrow 8[-13m + 9n - 22p]\\[1em] \Rightarrow -104m + 72n - 176p

Hence, 8[m+2n−p−7(2m−n+3p)]=−104m+72n−176p\bm{8[m + 2n - p - 7(2m - n + 3p)] = -104m + 72n - 176p}.

Question 26

Simplify:

{9−(4p−6q)}−{3q−(5p−10)}\big\lbrace 9 - (4p - 6q)\big\rbrace - \big\lbrace 3q - (5p - 10)\big\rbrace

Answer

Solving,

⇒{9−(4p−6q)}−{3q−(5p−10)}⇒{9−4p+6q}−{3q−5p+10}⇒9−4p+6q−3q+5p−10⇒(−4+5)p+(6−3)q+(9−10)⇒p+3q−1\Rightarrow \big\lbrace 9 - (4p - 6q)\big\rbrace - \big\lbrace 3q - (5p - 10)\big\rbrace \\[1em] \Rightarrow \big\lbrace 9 - 4p + 6q\big\rbrace - \big\lbrace 3q - 5p + 10\big\rbrace \\[1em] \Rightarrow 9 - 4p + 6q - 3q + 5p - 10 \\[1em] \Rightarrow (-4 + 5)p + (6 - 3)q + (9 - 10) \\[1em] \Rightarrow p + 3q - 1

Hence, {9−(4p−6q)}−{3q−(5p−10)}=p+3q−1\bm{ \big\lbrace 9 - (4p - 6q)\big\rbrace - \big\lbrace 3q - (5p - 10)\big\rbrace = p + 3q - 1}.

Question 27

Simplify:

2[a−3{a+5(a−2)+7}]2[a - 3 \big\lbrace a + 5(a - 2) + 7\big\rbrace]

Answer

Solving,

⇒2[a−3{a+5(a−2)+7}]⇒2[a−3{a+5a−10+7}]⇒2[a−3{6a−3}]⇒2[a−18a+9]⇒2[−17a+9]⇒−34a+18\Rightarrow 2[a - 3 \big\lbrace a + 5(a - 2) + 7\big\rbrace]\\[1em] \Rightarrow 2[a - 3 \big\lbrace a + 5a - 10 + 7\big\rbrace] \\[1em] \Rightarrow 2[a - 3 \big\lbrace 6a - 3\big\rbrace]\\[1em] \Rightarrow 2[a - 18a + 9] \\[1em] \Rightarrow 2[-17a + 9]\\[1em] \Rightarrow -34a + 18

Hence, 2[a−3{a+5(a−2)+7}]=−34a+18\bm{2[a - 3 \big\lbrace a + 5(a - 2) + 7\big\rbrace] = -34a + 18}.

Question 28

Simplify:

5a−[6a−{9a−(10a−4a−3a‾)}]5a - [6a - \big\lbrace 9a - (10a - \overline{4a - 3a})\big\rbrace]

Answer

Solving,

⇒5a−[6a−{9a−(10a−4a−3a‾)}]⇒5a−[6a−{9a−(10a−a)}]⇒5a−[6a−{9a−9a}]⇒5a−[6a−0]⇒5a−6a⇒−a\Rightarrow 5a - [6a - \big\lbrace 9a - (10a - \overline{4a - 3a})\big\rbrace]\\[1em] \Rightarrow 5a - [6a - \big\lbrace 9a - (10a - a)\big\rbrace] \\[1em] \Rightarrow 5a - [6a - \big\lbrace 9a - 9a\big\rbrace] \\[1em] \Rightarrow 5a - [6a - 0] \\[1em] \Rightarrow 5a - 6a\\[1em] \Rightarrow -a

Hence, 5a−[6a−{9a−(10a−4a−3a‾)}]=−a\bm{5a - [6a - \big\lbrace 9a - (10a - \overline{4a - 3a})\big\rbrace] = -a}.

Question 29

Simplify:

9x+5−[4x−{3x−2(4x−3)}]9x + 5 - [4x - \big\lbrace 3x - 2(4x - 3)\big\rbrace]

Answer

Solving,

⇒9x+5−[4x−{3x−2(4x−3)}]⇒9x+5−[4x−{3x−8x+6}]⇒9x+5−[4x−{−5x+6}]⇒9x+5−[4x+5x−6]⇒9x+5−[9x−6]⇒9x+5−9x+6⇒11\Rightarrow 9x + 5 - [4x - \big\lbrace 3x - 2(4x - 3)\big\rbrace]\\[1em] \Rightarrow 9x + 5 - [4x - \big\lbrace 3x - 8x + 6\big\rbrace] \\[1em] \Rightarrow 9x + 5 - [4x - \big\lbrace -5x + 6\big\rbrace]\\[1em] \Rightarrow 9x + 5 - [4x + 5x - 6] \\[1em] \Rightarrow 9x + 5 - [9x - 6]\\[1em] \Rightarrow 9x + 5 - 9x + 6 \\[1em] \Rightarrow 11

Hence, 9x+5−[4x−{3x−2(4x−3)}]=11\bm{9x + 5 - [4x - \big\lbrace 3x - 2(4x - 3)\big\rbrace] = 11}.

Question 30

Simplify:

(x+y−z)x+(z+x−y)y−(x+y−z)z(x + y - z)x + (z + x - y)y - (x + y - z)z

Answer

Solving,

⇒(x+y−z)x+(z+x−y)y−(x+y−z)z⇒(x2+xy−xz)+(yz+xy−y2)−(xz+yz−z2)⇒x2+xy−xz+yz+xy−y2−xz−yz+z2⇒x2−y2+z2+(1+1)xy+(−1−1)xz+(1−1)yz⇒x2−y2+z2+2xy−2xz\Rightarrow (x + y - z)x + (z + x - y)y - (x + y - z)z\\[1em] \Rightarrow (x^2 + xy - xz) + (yz + xy - y^2) - (xz + yz - z^2)\\[1em] \Rightarrow x^2 + xy - xz + yz + xy - y^2 - xz - yz + z^2\\[1em] \Rightarrow x^2 - y^2 + z^2 + (1 + 1)xy + (-1 - 1)xz + (1 - 1)yz\\[1em] \Rightarrow x^2 - y^2 + z^2 + 2xy - 2xz

Hence, (x+y−z)x+(z+x−y)y−(x+y−z)z=x2−y2+z2+2xy−2xz\bm{(x + y - z)x + (z + x - y)y - (x + y - z)z = x^2 - y^2 + z^2 + 2xy - 2xz}.

Question 31

Simplify:

−1[a−3{b−4(a−b‾−8)+4a}+10]-1[a - 3 \big\lbrace b - 4(\overline{a - b} - 8) + 4a\big\rbrace + 10]

Answer

Solving,

⇒−1[a−3{b−4(a−b‾−8)+4a}+10]⇒−1[a−3{b−4(a−b−8)+4a}+10]⇒−1[a−3{b−4a+4b+32+4a}+10]⇒−1[a−3{5b+32}+10]⇒−1[a−15b−96+10]⇒−1[a−15b−86]⇒−a+15b+86\Rightarrow -1[a - 3 \big\lbrace b - 4(\overline{a - b} - 8) + 4a\big\rbrace + 10]\\[1em] \Rightarrow -1[a - 3 \big\lbrace b - 4(a - b - 8) + 4a\big\rbrace + 10] \\[1em] \Rightarrow -1[a - 3 \big\lbrace b - 4a + 4b + 32 + 4a\big\rbrace + 10] \\[1em] \Rightarrow -1[a - 3 \big\lbrace 5b + 32\big\rbrace + 10]\\[1em] \Rightarrow -1[a - 15b - 96 + 10] \\[1em] \Rightarrow -1[a - 15b - 86]\\[1em] \Rightarrow -a + 15b + 86

Hence, −1[a−3{b−4(a−b‾−8)+4a}+10]=−a+15b+86\bm{-1[a - 3 \big\lbrace b - 4(\overline{a - b} - 8) + 4a\big\rbrace + 10] = -a + 15b + 86}.

Question 32

Simplify:

p2−[x2−{x2−(q2−x2−q2‾)−2y2}]p^2 - [x^2 - \big\lbrace x^2 - (q^2 - \overline{x^2 - q^2}) - 2y^2\big\rbrace]

Answer

Solving,

⇒p2−[x2−{x2−(q2−x2−q2‾)−2y2}]⇒p2−[x2−{x2−(q2−x2+q2)−2y2}]⇒p2−[x2−{x2−(2q2−x2)−2y2}]⇒p2−[x2−{x2−2q2+x2−2y2}]⇒p2−[x2−{2x2−2q2−2y2}]⇒p2−[x2−2x2+2q2+2y2]⇒p2−[−x2+2q2+2y2]⇒p2+x2−2q2−2y2\Rightarrow p^2 - [x^2 - \big\lbrace x^2 - (q^2 - \overline{x^2 - q^2}) - 2y^2\big\rbrace]\\[1em] \Rightarrow p^2 - [x^2 - \big\lbrace x^2 - (q^2 - x^2 + q^2) - 2y^2\big\rbrace] \\[1em] \Rightarrow p^2 - [x^2 - \big\lbrace x^2 - (2q^2 - x^2) - 2y^2\big\rbrace]\\[1em] \Rightarrow p^2 - [x^2 - \big\lbrace x^2 - 2q^2 + x^2 - 2y^2\big\rbrace] \\[1em] \Rightarrow p^2 - [x^2 - \big\lbrace 2x^2 - 2q^2 - 2y^2\big\rbrace]\\[1em] \Rightarrow p^2 - [x^2 - 2x^2 + 2q^2 + 2y^2] \\[1em] \Rightarrow p^2 - [-x^2 + 2q^2 + 2y^2] \\[1em] \Rightarrow p^2 + x^2 - 2q^2 - 2y^2

Hence, p2−[x2−{x2−(q2−x2−q2‾)−2y2}]=p2+x2−2q2−2y2\bm{p^2 - [x^2 - \big\lbrace x^2 - (q^2 - \overline{x^2 - q^2}) - 2y^2\big\rbrace] = p^2 + x^2 - 2q^2 - 2y^2}.

Question 33

Simplify:

10−{4a−(7−a−5‾)−(5a−1+a‾)}10 - \big\lbrace 4a - (7 - \overline{a - 5}) - (5a - \overline{1 + a})\big\rbrace

Answer

Solving,

⇒10−{4a−(7−a−5‾)−(5a−1+a‾)}⇒10−{4a−(7−a+5)−(5a−1−a)}⇒10−{4a−(12−a)−(4a−1)}⇒10−{4a−12+a−4a+1}⇒10−{a−11}⇒10−a+11⇒21−a\Rightarrow 10 - \big\lbrace 4a - (7 - \overline{a - 5}) - (5a - \overline{1 + a})\big\rbrace\\[1em] \Rightarrow 10 - \big\lbrace 4a - (7 - a + 5) - (5a - 1 - a)\big\rbrace \\[1em] \Rightarrow 10 - \big\lbrace 4a - (12 - a) - (4a - 1)\big\rbrace\\[1em] \Rightarrow 10 - \big\lbrace 4a - 12 + a - 4a + 1\big\rbrace \\[1em] \Rightarrow 10 - \big\lbrace a - 11\big\rbrace\\[1em] \Rightarrow 10 - a + 11 \\[1em] \Rightarrow 21 - a

Hence, 10−{4a−(7−a−5‾)−(5a−1+a‾)}=21−a\bm{10 - \big\lbrace 4a - (7 - \overline{a - 5}) - (5a - \overline{1 + a})\big\rbrace = 21 - a}.

Question 34

Simplify:

7a−[8a−{11a−(12a−6a−5a‾)}]7a - [8a - \big\lbrace 11a - (12a - \overline{6a - 5a})\big\rbrace]

Answer

Solving,

⇒7a−[8a−{11a−(12a−6a−5a‾)}]⇒7a−[8a−{11a−(12a−a)}]⇒7a−[8a−{11a−11a}]⇒7a−[8a−0]⇒7a−8a⇒−a\Rightarrow 7a - [8a - \big\lbrace 11a - (12a - \overline{6a - 5a})\big\rbrace]\\[1em] \Rightarrow 7a - [8a - \big\lbrace 11a - (12a - a)\big\rbrace] \\[1em] \Rightarrow 7a - [8a - \big\lbrace 11a - 11a\big\rbrace] \\[1em] \Rightarrow 7a - [8a - 0] \\[1em] \Rightarrow 7a - 8a\\[1em] \Rightarrow -a

Hence, 7a−[8a−{11a−(12a−6a−5a‾)}]=−a\bm{7a - [8a - \big\lbrace 11a - (12a - \overline{6a - 5a})\big\rbrace] = -a}.

Question 35

Simplify:

8x−[4y−{4x+(2x−2y−2x‾)}]8x - [4y - \big\lbrace 4x + (2x - \overline{2y - 2x})\big\rbrace]

Answer

Solving,

⇒8x−[4y−{4x+(2x−2y−2x‾)}]⇒8x−[4y−{4x+(2x−2y+2x)}]⇒8x−[4y−{4x+(4x−2y)}]⇒8x−[4y−{4x+4x−2y}]⇒8x−[4y−{8x−2y}]⇒8x−[4y−8x+2y]⇒8x−[6y−8x]⇒8x−6y+8x⇒16x−6y\Rightarrow 8x - [4y - \big\lbrace 4x + (2x - \overline{2y - 2x})\big\rbrace]\\[1em] \Rightarrow 8x - [4y - \big\lbrace 4x + (2x - 2y + 2x)\big\rbrace] \\[1em] \Rightarrow 8x - [4y - \big\lbrace 4x + (4x - 2y)\big\rbrace]\\[1em] \Rightarrow 8x - [4y - \big\lbrace 4x + 4x - 2y\big\rbrace] \\[1em] \Rightarrow 8x - [4y - \big\lbrace 8x - 2y\big\rbrace]\\[1em] \Rightarrow 8x - [4y - 8x + 2y] \\[1em] \Rightarrow 8x - [6y - 8x]\\[1em] \Rightarrow 8x - 6y + 8x \\[1em] \Rightarrow 16x - 6y

Hence, 8x−[4y−{4x+(2x−2y−2x‾)}]=16x−6y\bm{8x - [4y - \big\lbrace 4x + (2x - \overline{2y - 2x})\big\rbrace] = 16x - 6y}.

Question 36

Simplify:

x−(3y−4z−3x‾+2z−5y−7x‾)x - (3y - \overline{4z - 3x} + 2z - \overline{5y - 7x})

Answer

Solving,

⇒x−(3y−4z−3x‾+2z−5y−7x‾)⇒x−(3y−4z+3x+2z−5y+7x)⇒x−[(3+7)x+(3−5)y+(−4+2)z]⇒x−(10x−2y−2z)⇒x−10x+2y+2z⇒−9x+2y+2z\Rightarrow x - (3y - \overline{4z - 3x} + 2z - \overline{5y - 7x})\\[1em] \Rightarrow x - (3y - 4z + 3x + 2z - 5y + 7x) \\[1em] \Rightarrow x - [(3 + 7)x + (3 - 5)y + (-4 + 2)z]\\[1em] \Rightarrow x - (10x - 2y - 2z)\\[1em] \Rightarrow x - 10x + 2y + 2z \\[1em] \Rightarrow -9x + 2y + 2z

Hence, x−(3y−4z−3x‾+2z−5y−7x‾)=−9x+2y+2z\bm{x - (3y - \overline{4z - 3x} + 2z - \overline{5y - 7x}) = -9x + 2y + 2z}.

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