(5x+9)(x-7)=0

Solution for (5x+9)(x-7)=0 equation:

(5x+9)(x-7)=0

We multiply parentheses ..

(+5x^2-35x+9x-63)=0

We get rid of parentheses

5x^2-35x+9x-63=0

We add all the numbers together, and all the variables

5x^2-26x-63=0

a = 5; b = -26; c = -63;
Δ = b2-4ac
Δ = -262-4·5·(-63)
Δ = 1936
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1936}=44$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-26)-44}{2*5}=\frac{-18}{10}
=-1+4/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-26)+44}{2*5}=\frac{70}{10}
=7
$