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Chapter 12

Fundamental Concepts of Algebra — Exercise 12(E)

Class - 6 Concise Mathematics Selina



Exercise 12(E)

Question 1(i)

Divide:

3a3a by aa

Answer

Solving,

⇒3aa\Rightarrow \dfrac{3a}{a}

⇒3\Rightarrow 3

Hence, 3aa=3\bm{\dfrac{3a}{a} = 3}.

Question 1(ii)

Divide:

15x15x by 3x3x

Answer

Solving,

⇒15x3x\Rightarrow \dfrac{15x}{3x}

⇒5\Rightarrow 5

Hence, 15x3x=5\bm{\dfrac{15x}{3x} = 5}.

Question 1(iii)

Divide:

16m16m by 4

Answer

Solving,

⇒16m4\Rightarrow \dfrac{16m}{4}

⇒4m\Rightarrow 4m

Hence, 16m4=4m\bm{\dfrac{16m}{4} = 4m}.

Question 1(iv)

Divide:

20x220x^2 by 5x5x

Answer

Solving,

⇒20x25x⇒4x2−1⇒4x\Rightarrow \dfrac{20x^2}{5x} \\[1em] \Rightarrow 4x^{2-1} \\[1em] \Rightarrow 4x

Hence, 20x25x=4x\bm{\dfrac{20x^2}{5x} = 4x}.

Question 1(v)

Divide:

30p230p^2 by 10p210p^2

Answer

Solving,

⇒30p210p2\Rightarrow \dfrac{30p^2}{10p^2}

⇒3\Rightarrow 3

Hence, 30p210p2=3\bm{\dfrac{30p^2}{10p^2} = 3}.

Question 1(vi)

Divide:

14a3b314a^3b^3 by 2a22a^2

Answer

Solving,

⇒14a3b32a2⇒7a3−2b3⇒7ab3\Rightarrow \dfrac{14a^3b^3}{2a^2} \\[1em] \Rightarrow 7a^{3-2}b^3 \\[1em] \Rightarrow 7ab^3

Hence, 14a3b32a2=7ab3\bm{\dfrac{14a^3b^3}{2a^2} = 7ab^3}.

Question 1(vii)

Divide:

18pqr218pqr^2 by 3pq3pq

Answer

Solving,

⇒18pqr23pq\Rightarrow \dfrac{18pqr^2}{3pq}

⇒6r2\Rightarrow 6r^2

Hence, 18pqr23pq=6r2\bm{\dfrac{18pqr^2}{3pq} = 6r^2}.

Question 1(viii)

Divide:

100 by 50b50b

Answer

Solving,

⇒10050b=2b\Rightarrow \dfrac{100}{50b} = \dfrac{2}{b}

Hence, 10050b=2b\bm{\dfrac{100}{50b} = \dfrac{2}{b}}.

Question 2(i)

Simplify:

2x5÷x22x^5 \div x^2

Answer

Solving,

⇒2x5x2⇒2x5−2⇒2x3\Rightarrow \dfrac{2x^5}{x^2} \\[1em] \Rightarrow 2x^{5-2} \\[1em] \Rightarrow 2x^3

Hence, 2x5÷x2=2x3\bm{2x^5 \div x^2 = 2x^3}.

Question 2(ii)

Simplify:

6a8÷3a36a^8 \div 3a^3

Answer

Solving,

⇒6a83a3⇒2a8−3⇒2a5\Rightarrow \dfrac{6a^8}{3a^3} \\[1em] \Rightarrow 2a^{8-3} \\[1em] \Rightarrow 2a^5

Hence, 6a8÷3a3=2a5\bm{6a^8 \div 3a^3 = 2a^5}.

Question 2(iii)

Simplify:

20xy÷−5xy20xy \div -5xy

Answer

Solving,

⇒20xy−5xy\Rightarrow \dfrac{20xy}{-5xy}

⇒−4\Rightarrow -4

Hence, 20xy÷−5xy=−4\bm{20xy \div -5xy = -4}.

Question 2(iv)

Simplify:

−24a2b2c2÷6ab-24a^2b^2c^2 \div 6ab

Answer

Solving,

⇒−24a2b2c26ab⇒−4a2−1b2−1c2⇒−4abc2\Rightarrow \dfrac{-24a^2b^2c^2}{6ab} \\[1em] \Rightarrow -4a^{2-1}b^{2-1}c^2 \\[1em] \Rightarrow -4abc^2

Hence, −24a2b2c2÷6ab=−4abc2\bm{-24a^2b^2c^2 \div 6ab = -4abc^2}.

Question 2(v)

Simplify:

−5x2y÷xy2-5x^2y \div xy^2

Answer

Solving,

⇒−5x2yxy2⇒−5x2−1y2−1⇒−5xy\Rightarrow \dfrac{-5x^2y}{xy^2} \\[1em] \Rightarrow \dfrac{-5x^{2-1}}{y^{2-1}}\\[1em] \Rightarrow \dfrac{-5x}{y}

Hence, −5x2y÷xy2=−5xy\bm{-5x^2y \div xy^2 = \dfrac{-5x}{y}}.

Question 2(vi)

Simplify:

40p3q4r5÷10p3q40p^3q^4r^5 \div 10p^3q

Answer

Solving,

⇒40p3q4r510p3q⇒4q4−1r5⇒4q3r5\Rightarrow \dfrac{40p^3q^4r^5}{10p^3q} \\[1em] \Rightarrow 4q^{4-1}r^5 \\[1em] \Rightarrow 4q^3r^5

Hence, 40p3q4r5÷10p3q=4q3r5\bm{40p^3q^4r^5 \div 10p^3q = 4q^3r^5}.

Question 2(vii)

Simplify:

−64x4y3z÷4x3y2z-64x^4y^3z \div 4x^3y^2z

Answer

Solving,

⇒−64x4y3z4x3y2z⇒−16x4−3y3−2⇒−16xy\Rightarrow \dfrac{-64x^4y^3z}{4x^3y^2z} \\[1em] \Rightarrow -16x^{4-3}y^{3-2} \\[1em] \Rightarrow -16xy

Hence, −64x4y3z÷4x3y2z=−16xy\bm{-64x^4y^3z \div 4x^3y^2z = -16xy}.

Question 2(viii)

Simplify:

35xy5÷7x2y435xy^5 \div 7x^2y^4

Answer

Solving,

⇒35xy57x2y4⇒5y5−4x2−1⇒5yx\Rightarrow \dfrac{35xy^5}{7x^2y^4} \\[1em] \Rightarrow \dfrac{5y^{5-4}}{x^{2-1}} \\[1em] \Rightarrow \dfrac{5y}{x}

Hence, 35xy5÷7x2y4=5yx\bm{35xy^5 \div 7x^2y^4 = \dfrac{5y}{x}}.

Question 3(i)

Divide:

−3m4-\dfrac{3m}{4} by 2m2m

Answer

Solving,

⇒−3m4÷2m⇒−3m4×12m⇒−3m8m⇒−38\Rightarrow -\dfrac{3m}{4} \div 2m \\[1em] \Rightarrow -\dfrac{3m}{4} \times \dfrac{1}{2m} \\[1em] \Rightarrow \dfrac{-3m}{8m} \\[1em] \Rightarrow \dfrac{-3}{8}

Hence, −3m4÷2m=−38\bm{-\dfrac{3m}{4} \div 2m = \dfrac{-3}{8}}.

Question 3(ii)

Divide:

−15p6q8-15p^6q^8 by −5p6q7-5p^6q^7

Answer

Solving,

⇒−15p6q8−5p6q7⇒3q8−7⇒3q\Rightarrow \dfrac{-15p^6q^8}{-5p^6q^7} \\[1em] \Rightarrow 3q^{8-7} \\[1em] \Rightarrow 3q

Hence, −15p6q8−5p6q7=3q\bm{\dfrac{-15p^6q^8}{-5p^6q^7} = 3q}.

Question 3(iii)

Divide:

−21m5n7-21m^5n^7 by 14m2n214m^2n^2

Answer

Solving,

⇒−21m5n714m2n2⇒−32m5−2n7−2⇒−32m3n5\Rightarrow \dfrac{-21m^5n^7}{14m^2n^2} \\[1em] \Rightarrow \dfrac{-3}{2}m^{5-2}n^{7-2} \\[1em] \Rightarrow \dfrac{-3}{2}m^3n^5

Hence, −21m5n714m2n2=−32m3n5\bm{\dfrac{-21m^5n^7}{14m^2n^2} = \dfrac{-3}{2}m^3n^5}.

Question 3(iv)

Divide:

36a4x5y636a^4x^5y^6 by 4x2a3y24x^2a^3y^2

Answer

Solving,

⇒36a4x5y64x2a3y2⇒9a4−3x5−2y6−2⇒9ax3y4\Rightarrow \dfrac{36a^4x^5y^6}{4x^2a^3y^2} \\[1em] \Rightarrow 9a^{4-3}x^{5-2}y^{6-2} \\[1em] \Rightarrow 9ax^3y^4

Hence, 36a4x5y64x2a3y2=9ax3y4\bm{\dfrac{36a^4x^5y^6}{4x^2a^3y^2} = 9ax^3y^4}.

Question 3(v)

Divide:

20x3a620x^3a^6 by 5xy5xy

Answer

Solving,

⇒20x3a65xy⇒4x3−1a6y⇒4x2a6y\Rightarrow \dfrac{20x^3a^6}{5xy} \\[1em] \Rightarrow \dfrac{4x^{3-1}a^6}{y} \\[1em] \Rightarrow \dfrac{4x^2a^6}{y}

Hence, 20x3a65xy=4x2a6y\bm{\dfrac{20x^3a^6}{5xy} = \dfrac{4x^2a^6}{y}}.

Question 3(vi)

Divide:

28a2b3c2\dfrac{28a^2b^3}{c^2} by 4abc4abc

Answer

Solving,

⇒28a2b3c2÷4abc⇒28a2b3c2×14abc⇒28a2b34abc3⇒7ab2c3\Rightarrow \dfrac{28a^2b^3}{c^2} \div 4abc \\[1em] \Rightarrow \dfrac{28a^2b^3}{c^2} \times \dfrac{1}{4abc} \\[1em] \Rightarrow \dfrac{28a^2b^3}{4abc^3} \\[1em] \Rightarrow \dfrac{7ab^2}{c^3}

Hence, 28a2b3c2÷4abc=7ab2c3\bm{\dfrac{28a^2b^3}{c^2} \div 4abc = \dfrac{7ab^2}{c^3}}.

Question 3(vii)

Divide:

2a29b2\dfrac{2a^2}{9b^2} by 3b2a\dfrac{3b}{2a}

Answer

Solving,

⇒2a29b2÷3b2a⇒2a29b2×2a3b⇒4a327b3\Rightarrow \dfrac{2a^2}{9b^2} \div \dfrac{3b}{2a} \\[1em] \Rightarrow \dfrac{2a^2}{9b^2} \times \dfrac{2a}{3b} \\[1em] \Rightarrow \dfrac{4a^3}{27b^3}

Hence, 2a29b2÷3b2a=4a327b3\bm{\dfrac{2a^2}{9b^2} \div \dfrac{3b}{2a} = \dfrac{4a^3}{27b^3}}.

Question 3(viii)

Divide:

−5.5x2y\dfrac{-5.5x^2}{y} by 11xy\dfrac{11x}{y}

Answer

Solving,

⇒−5.5x2y÷11xy⇒−5.5x2y×y11x⇒−5.5x2y11xy⇒−5.5x11⇒−x2⇒−0.5x\Rightarrow \dfrac{-5.5x^2}{y} \div \dfrac{11x}{y} \\[1em] \Rightarrow \dfrac{-5.5x^2}{y} \times \dfrac{y}{11x} \\[1em] \Rightarrow \dfrac{-5.5x^2y}{11xy} \\[1em] \Rightarrow \dfrac{-5.5x}{11} \\[1em] \Rightarrow -\dfrac{x}{2} \\[1em] \Rightarrow -0.5x

Hence, −5.5x2y÷11xy=−x2=−0.5x\bm{\dfrac{-5.5x^2}{y} \div \dfrac{11x}{y} = -\dfrac{x}{2} = -0.5x}.

Question 3(ix)

Divide:

64x2y2z2\dfrac{64x^2y^2}{z^2} by 8xyz\dfrac{8xy}{z}

Answer

Solving,

⇒64x2y2z2÷8xyz⇒64x2y2z2×z8xy⇒64x2y2z8xyz2⇒8xyz\Rightarrow \dfrac{64x^2y^2}{z^2} \div \dfrac{8xy}{z} \\[1em] \Rightarrow \dfrac{64x^2y^2}{z^2} \times \dfrac{z}{8xy} \\[1em] \Rightarrow \dfrac{64x^2y^2z}{8xyz^2} \\[1em] \Rightarrow \dfrac{8xy}{z}

Hence, 64x2y2z2÷8xyz=8xyz\bm{\dfrac{64x^2y^2}{z^2} \div \dfrac{8xy}{z} = \dfrac{8xy}{z}}.

Question 4(i)

Simplify:

−15m5n2−3m5\dfrac{-15m^5n^2}{-3m^5}

Answer

Solving,

⇒−15m5n2−3m5\Rightarrow \dfrac{-15m^5n^2}{-3m^5}

⇒5n2\Rightarrow 5n^2

Hence, −15m5n2−3m5=5n2\bm{\dfrac{-15m^5n^2}{-3m^5} = 5n^2}.

Question 4(ii)

Simplify:

35x4y2−15x2y2\dfrac{35x^4y^2}{-15x^2y^2}

Answer

Solving,

⇒35x4y2−15x2y2⇒−7x4−23⇒−7x23\Rightarrow \dfrac{35x^4y^2}{-15x^2y^2} \\[1em] \Rightarrow \dfrac{-7x^{4-2}}{3} \\[1em] \Rightarrow \dfrac{-7x^2}{3}

Hence, 35x4y2−15x2y2=−7x23\bm{\dfrac{35x^4y^2}{-15x^2y^2} = \dfrac{-7x^2}{3}}.

Question 4(iii)

Simplify:

−24x6y26x6y\dfrac{-24x^6y^2}{6x^6y}

Answer

Solving,

⇒−24x6y26x6y⇒−4y2−1⇒−4y\Rightarrow \dfrac{-24x^6y^2}{6x^6y} \\[1em] \Rightarrow -4y^{2-1} \\[1em] \Rightarrow -4y

Hence, −24x6y26x6y=−4y\bm{\dfrac{-24x^6y^2}{6x^6y} = -4y}.

Question 5(i)

Divide:

9x3−6x29x^3 - 6x^2 by 3x3x

Answer

Solving,

⇒9x3−6x23x⇒9x33x−6x23x⇒3x2−2x\Rightarrow \dfrac{9x^3 - 6x^2}{3x} \\[1em] \Rightarrow \dfrac{9x^3}{3x} - \dfrac{6x^2}{3x} \\[1em] \Rightarrow 3x^2 - 2x

Hence, 9x3−6x23x=3x2−2x\bm{\dfrac{9x^3 - 6x^2}{3x} = 3x^2 - 2x}.

Question 5(ii)

Divide:

6m2−16m3+10m46m^2 - 16m^3 + 10m^4 by −2m-2m

Answer

Solving,

⇒6m2−16m3+10m4−2m⇒6m2−2m−16m3−2m+10m4−2m⇒−3m−(−8m2)+(−5m3)⇒−3m+8m2−5m3\Rightarrow \dfrac{6m^2 - 16m^3 + 10m^4}{-2m} \\[1em] \Rightarrow \dfrac{6m^2}{-2m} - \dfrac{16m^3}{-2m} + \dfrac{10m^4}{-2m} \\[1em] \Rightarrow -3m - (-8m^2) + (-5m^3) \\[1em] \Rightarrow -3m + 8m^2 - 5m^3

Hence, 6m2−16m3+10m4−2m=−3m+8m2−5m3\bm{\dfrac{6m^2 - 16m^3 + 10m^4}{-2m} = -3m + 8m^2 - 5m^3}.

Question 5(iii)

Divide:

15x3y2+25x2y3−36x4y415x^3y^2 + 25x^2y^3 - 36x^4y^4 by 5x2y25x^2y^2

Answer

Solving,

⇒15x3y2+25x2y3−36x4y45x2y2⇒15x3y25x2y2+25x2y35x2y2−36x4y45x2y2⇒3x+5y−365x2y2\Rightarrow \dfrac{15x^3y^2 + 25x^2y^3 - 36x^4y^4}{5x^2y^2} \\[1em] \Rightarrow \dfrac{15x^3y^2}{5x^2y^2} + \dfrac{25x^2y^3}{5x^2y^2} - \dfrac{36x^4y^4}{5x^2y^2} \\[1em] \Rightarrow 3x + 5y - \dfrac{36}{5}x^2y^2

Hence, 15x3y2+25x2y3−36x4y45x2y2=3x+5y−365x2y2\bm{\dfrac{15x^3y^2 + 25x^2y^3 - 36x^4y^4}{5x^2y^2} = 3x + 5y - \dfrac{36}{5}x^2y^2}.

Question 5(iv)

Divide:

36a3x5−24a4x4+18a5x336a^3x^5 - 24a^4x^4 + 18a^5x^3 by −6a3x3-6a^3x^3

Answer

Solving,

⇒36a3x5−24a4x4+18a5x3−6a3x3⇒36a3x5−6a3x3−24a4x4−6a3x3+18a5x3−6a3x3⇒−6x2−(−4ax)+(−3a2)⇒−6x2+4ax−3a2\Rightarrow \dfrac{36a^3x^5 - 24a^4x^4 + 18a^5x^3}{-6a^3x^3} \\[1em] \Rightarrow \dfrac{36a^3x^5}{-6a^3x^3} - \dfrac{24a^4x^4}{-6a^3x^3} + \dfrac{18a^5x^3}{-6a^3x^3} \\[1em] \Rightarrow -6x^2 - (-4ax) + (-3a^2) \\[1em] \Rightarrow -6x^2 + 4ax - 3a^2

Hence, 36a3x5−24a4x4+18a5x3−6a3x3=−6x2+4ax−3a2\bm{\dfrac{36a^3x^5 - 24a^4x^4 + 18a^5x^3}{-6a^3x^3} = -6x^2 + 4ax - 3a^2}.

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