(s-4)(7s+9)=

Solution for (s-4)(7s+9)= equation:

(s-4)(7s+9)=

We move all terms to the left:

(s-4)(7s+9)-()=0

We add all the numbers together, and all the variables

(s-4)(7s+9)=0

We multiply parentheses ..

(+7s^2+9s-28s-36)=0

We get rid of parentheses

7s^2+9s-28s-36=0

We add all the numbers together, and all the variables

7s^2-19s-36=0

a = 7; b = -19; c = -36;
Δ = b2-4ac
Δ = -192-4·7·(-36)
Δ = 1369
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$s_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$s_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1369}=37$
$s_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-19)-37}{2*7}=\frac{-18}{14}
=-1+2/7
$
$s_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-19)+37}{2*7}=\frac{56}{14}
=4
$