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

Solution for (1+u)(5u+7)=0 equation:

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

We add all the numbers together, and all the variables

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

We multiply parentheses ..

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

We get rid of parentheses

5u^2+7u+5u+7=0

We add all the numbers together, and all the variables

5u^2+12u+7=0

a = 5; b = 12; c = +7;
Δ = b2-4ac
Δ = 122-4·5·7
Δ = 4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4}=2$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(12)-2}{2*5}=\frac{-14}{10}
=-1+2/5
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(12)+2}{2*5}=\frac{-10}{10}
=-1
$