(7r-7)(1r+1)=0

Solution for (7r-7)(1r+1)=0 equation:

(7r-7)(1r+1)=0

We add all the numbers together, and all the variables

(7r-7)(r+1)=0

We multiply parentheses ..

(+7r^2+7r-7r-7)=0

We get rid of parentheses

7r^2+7r-7r-7=0

We add all the numbers together, and all the variables

7r^2-7=0

a = 7; b = 0; c = -7;
Δ = b2-4ac
Δ = 02-4·7·(-7)
Δ = 196
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{196}=14$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-14}{2*7}=\frac{-14}{14}
=-1
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+14}{2*7}=\frac{14}{14}
=1
$