(7+u)(4u-2)=0

Solution for (7+u)(4u-2)=0 equation:

(7+u)(4u-2)=0

We add all the numbers together, and all the variables

(u+7)(4u-2)=0

We multiply parentheses ..

(+4u^2-2u+28u-14)=0

We get rid of parentheses

4u^2-2u+28u-14=0

We add all the numbers together, and all the variables

4u^2+26u-14=0

a = 4; b = 26; c = -14;
Δ = b2-4ac
Δ = 262-4·4·(-14)
Δ = 900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{900}=30$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(26)-30}{2*4}=\frac{-56}{8}
=-7
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(26)+30}{2*4}=\frac{4}{8}
=1/2
$