(9t-1)(t+4)=0

Solution for (9t-1)(t+4)=0 equation:

(9t-1)(t+4)=0

We multiply parentheses ..

(+9t^2+36t-1t-4)=0

We get rid of parentheses

9t^2+36t-1t-4=0

We add all the numbers together, and all the variables

9t^2+35t-4=0

a = 9; b = 35; c = -4;
Δ = b2-4ac
Δ = 352-4·9·(-4)
Δ = 1369
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1369}=37$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(35)-37}{2*9}=\frac{-72}{18}
=-4
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(35)+37}{2*9}=\frac{2}{18}
=1/9
$