5t(4-t)=-25

Solution for 5t(4-t)=-25 equation:

5t(4-t)=-25

We move all terms to the left:

5t(4-t)-(-25)=0

We add all the numbers together, and all the variables

5t(-1t+4)-(-25)=0

We add all the numbers together, and all the variables

5t(-1t+4)+25=0

We multiply parentheses

-5t^2+20t+25=0

a = -5; b = 20; c = +25;
Δ = b2-4ac
Δ = 202-4·(-5)·25
Δ = 900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{900}=30$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-30}{2*-5}=\frac{-50}{-10}
=+5
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+30}{2*-5}=\frac{10}{-10}
=-1
$