11r+15=12r2

Solution for 11r+15=12r2 equation:

11r+15=12r^2

We move all terms to the left:

11r+15-(12r^2)=0

determiningTheFunctionDomain
-12r^2+11r+15=0

a = -12; b = 11; c = +15;
Δ = b2-4ac
Δ = 112-4·(-12)·15
Δ = 841
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{841}=29$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(11)-29}{2*-12}=\frac{-40}{-24}
=1+2/3
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(11)+29}{2*-12}=\frac{18}{-24}
=-3/4
$