P=3t^2+7t

Solution for P=3t^2+7t equation:

=3P^2+7P

We move all terms to the left:

-(3P^2+7P)=0

We get rid of parentheses

-3P^2-7P=0

a = -3; b = -7; c = 0;
Δ = b2-4ac
Δ = -72-4·(-3)·0
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$P_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$P_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$P_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-7)-7}{2*-3}=\frac{0}{-6}
=0
$
$P_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+7}{2*-3}=\frac{14}{-6}
=-2+1/3
$