(4)=8x^2+9x-7

Solution for (4)=8x^2+9x-7 equation:

(4)=8x^2+9x-7

We move all terms to the left:

(4)-(8x^2+9x-7)=0

We get rid of parentheses

-8x^2-9x+7+4=0

We add all the numbers together, and all the variables

-8x^2-9x+11=0

a = -8; b = -9; c = +11;
Δ = b2-4ac
Δ = -92-4·(-8)·11
Δ = 433
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-\sqrt{433}}{2*-8}=\frac{9-\sqrt{433}}{-16}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+\sqrt{433}}{2*-8}=\frac{9+\sqrt{433}}{-16}
$