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

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

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

We multiply parentheses ..

(+14x^2-10x+35x-25)=0

We get rid of parentheses

14x^2-10x+35x-25=0

We add all the numbers together, and all the variables

14x^2+25x-25=0

a = 14; b = 25; c = -25;
Δ = b2-4ac
Δ = 252-4·14·(-25)
Δ = 2025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2025}=45$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(25)-45}{2*14}=\frac{-70}{28}
=-2+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(25)+45}{2*14}=\frac{20}{28}
=5/7
$