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Solve :

12(x+2y)+53(3x2y)=32\dfrac{1}{2(x + 2y)}+\dfrac{5}{3(3x - 2y)} = -\dfrac{3}{2}

54(x+2y)35(3x2y)=6160\dfrac{5}{4(x + 2y)} - \dfrac{3}{5(3x - 2y)} = \dfrac{61}{60}

Linear Equations

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Answer

Given: 12(x+2y)+53(3x2y)=32\dfrac{1}{2(x + 2y)}+\dfrac{5}{3(3x - 2y)} = -\dfrac{3}{2}

54(x+2y)35(3x2y)=6160\dfrac{5}{4(x + 2y)} - \dfrac{3}{5(3x - 2y)} = \dfrac{61}{60}

Let 1x+2y\dfrac{1}{x + 2y} = a and 13x2y\dfrac{1}{3x - 2y} = b.

So, the equations are

12a+53b=32\dfrac{1}{2}a + \dfrac{5}{3}b = -\dfrac{3}{2}

Multiplying the complete equation with 6,

⇒ 3a + 10b = - 9 ……………………..(1)

54a35b=6160\dfrac{5}{4}a - \dfrac{3}{5}b = \dfrac{61}{60}

Multiplying the complete equation with 60,

⇒ 75a - 36b = 61 ……………………..(2)

Multiplying 25 in equation (1), we get

⇒ (3a + 10b = -9) x 25

⇒ 75a + 250b = -225 ……………….(3)

Subtracting equation (3) and (2), we get:

75a+250b=22575a36b=61286b=286b=286286\begin{matrix} & 75a & + & 250b & = & -225 \ & 75a & - & 36b & = & 61 \ & - & &- & & - \ \hline & & & 286b & = & -286 \ \Rightarrow & & & b & = & \dfrac{-286}{286} \ \end{matrix}

⇒ b = -1

Putting the value of b in equation (2), we get

⇒ 75a - 36 x (-1) = 61

⇒ 75a + 36 = 61

⇒ 75a = 61 - 36

⇒ 75a = 25

⇒ a = 2575=13\dfrac{25}{75} = \dfrac{1}{3}

So, 1x+2y\dfrac{1}{x + 2y} = a = 13\dfrac{1}{3} and 13x2y\dfrac{1}{3x - 2y} = b = -1

⇒ x + 2y = 3 and 3x - 2y = -1

Adding both equation, we get:

x+2y=33x2y=1+++4x=2x=24\begin{matrix} & x & + & 2y & = & 3 \ & 3x & - & 2y & = & -1 \ & + & &+ & & + \ \hline & 4x & & & = & 2 \ \Rightarrow &x & & & = & \dfrac{2}{4} \ \end{matrix}

⇒ x = 12\dfrac{1}{2}

And putting the value of x in equation x + 2y = 3

12\dfrac{1}{2} + 2y = 3

⇒ 2y = 3 - 12\dfrac{1}{2}

⇒ 2y = 52\dfrac{5}{2}

⇒ y = 54\dfrac{5}{4}

Hence, x = 12\dfrac{1}{2} and y = 54\dfrac{5}{4}.

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