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

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

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

We add all the numbers together, and all the variables

-2(u-7)(-1u+5)=0

We multiply parentheses ..

-2(-1u^2+5u+7u-35)=0

We multiply parentheses

2u^2-10u-14u+70=0

We add all the numbers together, and all the variables

2u^2-24u+70=0

a = 2; b = -24; c = +70;
Δ = b2-4ac
Δ = -242-4·2·70
Δ = 16
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16}=4$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-24)-4}{2*2}=\frac{20}{4}
=5
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-24)+4}{2*2}=\frac{28}{4}
=7
$