Y=9x^2-60x-21

Solution for Y=9x^2-60x-21 equation:

=9Y^2-60Y-21

We move all terms to the left:

-(9Y^2-60Y-21)=0

We get rid of parentheses

-9Y^2+60Y+21=0

a = -9; b = 60; c = +21;
Δ = b2-4ac
Δ = 602-4·(-9)·21
Δ = 4356
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4356}=66$
$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(60)-66}{2*-9}=\frac{-126}{-18}
=+7
$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(60)+66}{2*-9}=\frac{6}{-18}
=-1/3
$