r2+9=7r=

Solution for r2+9=7r= equation:

r2+9=7r=

We move all terms to the left:

r2+9-(7r)=0

We add all the numbers together, and all the variables

r^2-7r+9=0

a = 1; b = -7; c = +9;
Δ = b2-4ac
Δ = -72-4·1·9
Δ = 13
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

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