(x+5)(3x-5)=

Solution for (x+5)(3x-5)= equation:

(x+5)(3x-5)=

We move all terms to the left:

(x+5)(3x-5)-()=0

We add all the numbers together, and all the variables

(x+5)(3x-5)=0

We multiply parentheses ..

(+3x^2-5x+15x-25)=0

We get rid of parentheses

3x^2-5x+15x-25=0

We add all the numbers together, and all the variables

3x^2+10x-25=0

a = 3; b = 10; c = -25;
Δ = b2-4ac
Δ = 102-4·3·(-25)
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(10)-20}{2*3}=\frac{-30}{6}
=-5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(10)+20}{2*3}=\frac{10}{6}
=1+2/3
$