Use the quadratic formula to solve 9x2 + 6x – 17 = 0

Question

asked Mar 22, 2017 25.8k views

2 Answers

Arsenal · Answer 1 · 2017-03-26T23:01:10+0000

The standard form of a quadratic equation is :

ax² + bx + c = 0

And the quadratic formula is:

$x=(-b\pm√(b^2-4ac))/(2a)$ .

So, first step is to compare the given equation with the above equation to get the value of a, b and c.

So, a = 9, b = 6 and c = - 17.

Next step is to plug in these values in the above formula. Therefore,

$x=(-6\pm√(6^2-4*(9)*(-17)))/(2*9)$

$=(-6\pm√(36+612))/(18)$

$=(-6\pm√(648))/(18)$

$=(-6\pm√(324*2))/(18)$

$=(-6\pm√(324)*√(2))/(18)$

$=(-6\pm18*√(2))/(18)$

$=-(6)/(18) \pm(18√(2))/(18)$

$=-(1)/(3) \pm√(2)$ .

So, x =
$-(1)/(3) \pm√(2)$