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

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

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

We multiply parentheses ..

(+10x^2+16x+35x+56)=0

We get rid of parentheses

10x^2+16x+35x+56=0

We add all the numbers together, and all the variables

10x^2+51x+56=0

a = 10; b = 51; c = +56;
Δ = b2-4ac
Δ = 512-4·10·56
Δ = 361
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{361}=19$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(51)-19}{2*10}=\frac{-70}{20}
=-3+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(51)+19}{2*10}=\frac{-32}{20}
=-1+3/5
$