8(2x+5)*(-x+7)=0

Solution for 8(2x+5)*(-x+7)=0 equation:

8(2x+5)(-x+7)=0

We add all the numbers together, and all the variables

8(2x+5)(-1x+7)=0

We multiply parentheses ..

8(-2x^2+14x-5x+35)=0

We multiply parentheses

-16x^2+112x-40x+280=0

We add all the numbers together, and all the variables

-16x^2+72x+280=0

a = -16; b = 72; c = +280;
Δ = b2-4ac
Δ = 722-4·(-16)·280
Δ = 23104
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{23104}=152$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(72)-152}{2*-16}=\frac{-224}{-32}
=+7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(72)+152}{2*-16}=\frac{80}{-32}
=-2+1/2
$