0=4t^2-15t

Solution for 0=4t^2-15t equation:

0=4t^2-15t

We move all terms to the left:

0-(4t^2-15t)=0

We add all the numbers together, and all the variables

-(4t^2-15t)=0

We get rid of parentheses

-4t^2+15t=0

a = -4; b = 15; c = 0;
Δ = b2-4ac
Δ = 152-4·(-4)·0
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-15}{2*-4}=\frac{-30}{-8}
=3+3/4
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+15}{2*-4}=\frac{0}{-8}
=0
$