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

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

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

We add all the numbers together, and all the variables

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

We multiply parentheses ..

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

We multiply parentheses

5u^2-25u-35u+175=0

We add all the numbers together, and all the variables

5u^2-60u+175=0

a = 5; b = -60; c = +175;
Δ = b2-4ac
Δ = -602-4·5·175
Δ = 100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{100}=10$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-60)-10}{2*5}=\frac{50}{10}
=5
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-60)+10}{2*5}=\frac{70}{10}
=7
$