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Mathematics

Solve the following equation using quadratic formula:

x+32x+3=x+13x+2\dfrac{x + 3}{2x + 3} = \dfrac{x + 1}{3x + 2}

Quadratic Equations

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Answer

x+32x+3=x+13x+2(x+3)(3x+2)=(x+1)(2x+3)(3x2+2x+9x+6)=(2x2+3x+2x+3)3x2+11x+6=2x2+5x+33x22x2+11x5x+63=0x2+6x+3=0.\Rightarrow \dfrac{x + 3}{2x + 3} = \dfrac{x + 1}{3x + 2} \\[1em] \Rightarrow (x + 3)(3x + 2) = (x + 1)(2x + 3) \\[1em] \Rightarrow (3x^2 + 2x + 9x + 6) = (2x^2 + 3x + 2x + 3) \\[1em] \Rightarrow 3x^2 + 11x + 6 = 2x^2 + 5x + 3 \\[1em] \Rightarrow 3x^2 - 2x^2 + 11x - 5x + 6 - 3 = 0 \\[1em] \Rightarrow x^2 + 6x + 3 = 0.

Comparing equation x2 + 6x + 3 = 0 with ax2 + bx + c = 0, we get :

a = 1, b = 6 and c = 3.

By formula,

x = b±b24ac2a\dfrac{-b \pm \sqrt{b^2 - 4ac}}{2a}

Substituting values we get :

x=(6)±(6)24×(1)×(3)2×1=6±36122=6±242=6±6×42=6±262=2(3±6)2=3±6=3+6 or 36.\Rightarrow x = \dfrac{-(6) \pm \sqrt{(6)^2 - 4 \times (1) \times (3)}}{2 \times 1} \\[1em] = \dfrac{-6 \pm \sqrt{36 - 12}}{2} \\[1em] = \dfrac{-6 \pm \sqrt{24}}{2} \\[1em] = \dfrac{-6 \pm \sqrt{6 \times 4}}{2} \\[1em] = \dfrac{-6 \pm 2\sqrt{6}}{2} \\[1em] = \dfrac{2(-3 \pm \sqrt{6})}{2} \\[1em] = -3 \pm \sqrt{6} \\[1em] = -3 + \sqrt{6} \text{ or } -3 - \sqrt{6}.

Hence, x={(3+6),(36)}x = \Big{(-3 + \sqrt{6}), (-3 - \sqrt{6})\Big}.

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