(x+1)(-5x+10)=0

Solution for (x+1)(-5x+10)=0 equation:

(x+1)(-5x+10)=0

We multiply parentheses ..

(-5x^2+10x-5x+10)=0

We get rid of parentheses

-5x^2+10x-5x+10=0

We add all the numbers together, and all the variables

-5x^2+5x+10=0

a = -5; b = 5; c = +10;
Δ = b2-4ac
Δ = 52-4·(-5)·10
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-15}{2*-5}=\frac{-20}{-10}
=+2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+15}{2*-5}=\frac{10}{-10}
=-1
$