(r*r)+7r-30=0

Solution for (r*r)+7r-30=0 equation:

(r*r)+7r-30=0

We add all the numbers together, and all the variables

(+r*r)+7r-30=0

We add all the numbers together, and all the variables

7r+(+r*r)-30=0

We get rid of parentheses

7r+r*r-30=0

Wy multiply elements

r^2+7r-30=0

a = 1; b = 7; c = -30;
Δ = b2-4ac
Δ = 72-4·1·(-30)
Δ = 169
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{169}=13$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(7)-13}{2*1}=\frac{-20}{2}
=-10
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+13}{2*1}=\frac{6}{2}
=3
$