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Solve for x :

2(2x1x+3)3(x+32x1)=5,x2\Big(\dfrac{2x - 1}{x + 3}\Big) - 3\Big(\dfrac{x + 3}{2x - 1}\Big) = 5, x3,12-3, \dfrac{1}{2}

Quadratic Equations

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Answer

Given,

2(2x1x+3)3(x+32x1)=5 Taking y=2x1x+3 the equation becomes2y3y=52y23=5y2y25y3=02\Big(\dfrac{2x - 1}{x + 3}\Big) - 3\Big(\dfrac{x + 3}{2x - 1}\Big) = 5 \\[1em] \Rightarrow \text{ Taking } y = \dfrac{2x - 1}{x + 3} \text{ the equation becomes} \\[1em] \Rightarrow 2y - \dfrac{3}{y} = 5 \\[1em] \Rightarrow 2y^2 - 3 = 5y \\[1em] \Rightarrow 2y^2 - 5y - 3 = 0 \\[1em]

Comparing it with ax2 + bx + c = 0, we get
a = 2 , b = -5 , c = -3

By using formula, x=b±b24ac2ax = \dfrac{-b ± \sqrt{b^2 - 4ac}}{2a}

we obtain:

(5)±(5)24×2×32×25±25+2445±4945±745+74 or 574124 or 243 or 12\Rightarrow \dfrac{-(-5) ± \sqrt{(-5)^2 - 4 \times 2 \times -3}}{2 \times 2} \\[1em] \Rightarrow \dfrac{5 ± \sqrt{25 + 24}}{4} \\[1em] \Rightarrow \dfrac{5 ± \sqrt{49}}{4} \\[1em] \Rightarrow \dfrac{5 ± 7}{4} \\[1em] \Rightarrow \dfrac{5 + 7}{4} \text{ or } \dfrac{5 - 7}{4}\\[1em] \Rightarrow \dfrac{12}{4} \text{ or } \dfrac{-2}{4} \\[1em] \Rightarrow 3 \text{ or } -\dfrac{1}{2} \\[1em]

But,

y=2x1x+33=2x1x+3 or 12=2x1x+33(x+3)=2x1 or (x+3)=2(2x1)3x+9=2x1 or x3=4x23x2x=19 or x4x=2+3x=10 or 5x=1x=10 or x=15y = \dfrac{2x - 1}{x + 3} \\[1em] \therefore 3 = \dfrac{2x - 1}{x + 3} \text{ or } -\dfrac{1}{2} = \dfrac{2x - 1}{x + 3} \\[1em] \Rightarrow 3(x + 3) = 2x - 1 \text{ or } -(x + 3) = 2(2x - 1) \\[1em] \Rightarrow 3x + 9 = 2x - 1 \text{ or } -x - 3 = 4x - 2 \\[1em] \Rightarrow 3x - 2x = -1 - 9 \text{ or } -x - 4x = -2 + 3 \\[1em] \Rightarrow x = -10 \text{ or } -5x = 1 \\[1em] \Rightarrow x = -10 \text{ or } x = -\dfrac{1}{5} \\[1em]

Hence roots of the given equations are -10 , 15-\dfrac{1}{5}.

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