300=4h^2+10h

Solution for 300=4h^2+10h equation:

300=4h^2+10h

We move all terms to the left:

300-(4h^2+10h)=0

We get rid of parentheses

-4h^2-10h+300=0

a = -4; b = -10; c = +300;
Δ = b2-4ac
Δ = -102-4·(-4)·300
Δ = 4900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$h_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$h_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4900}=70$
$h_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-70}{2*-4}=\frac{-60}{-8}
=7+1/2
$
$h_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+70}{2*-4}=\frac{80}{-8}
=-10
$