Question

9x2 + 7x - 2 = 0

Solve using quadratic formula. class10​

Answer 1

9x2 + 7x - 2 = 0

=9x^2 +9x-2x -2

=9x(x +1 ) +2(x+1)

=(9x+2 ) ( x+1)

ANSWER:

=(9x+2 ) ( x+1)

Answer 2

ANSWER:

To Solve:

• 9x² + 7x - 2= 0

Solution:

$\text{We are given that,}\\\\:\longrightarrow9x^2+7x-2=0\\\\\text{We know that,}\\\\\text{For a quadratic equation, ax^2+bx+c=0 ,}\\\\\text{By Quadratic Formula,}\\\\:\hookrightarrow x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}\\\\\text{So, in this case, a = 9, b = 7, c = -2.}\\\\\text{Hence,}\\\\:\implies x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}\\\\:\implies x=\dfrac{-(7)\pm\sqrt{(7)^2-4(9)(-2)}}{2(9)}$

$:\implies x=\dfrac{-7\pm\sqrt{49+72}}{18}\\\\:\implies x=\dfrac{-7\pm\sqrt{121}}{18}\\\\:\implies x=\dfrac{-7\pm11}{18}\\\\:\implies x=\dfrac{-7+11}{18}\:\:or\:\:x=\dfrac{-7-11}{18}\\\\:\implies x=\dfrac{4\!\!\!/^{\:2}}{18\!\!\!\!\!/^{\:\:9}}\:\:or\:\:x=\dfrac{-18\!\!\!\!\!/}{18\!\!\!\!\!/}\\\\:\implies x=\dfrac{2}{9}\:\:and\:\:x=-1\\\\\text{So,}\\\\\bf{:\implies x=\dfrac{2}{9}\:\:\:and\:\:\:-1}$

Formula Used:

$\text{For a quadratic equation, ax^2+bx+c=0 ,}\\\\\text{By Quadratic Formula,}\\\\:\hookrightarrow x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$