(9x+10)(7x+8)=0

Solution for (9x+10)(7x+8)=0 equation:

(9x+10)(7x+8)=0

We multiply parentheses ..

(+63x^2+72x+70x+80)=0

We get rid of parentheses

63x^2+72x+70x+80=0

We add all the numbers together, and all the variables

63x^2+142x+80=0

a = 63; b = 142; c = +80;
Δ = b2-4ac
Δ = 1422-4·63·80
Δ = 4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4}=2$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(142)-2}{2*63}=\frac{-144}{126}
=-1+1/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(142)+2}{2*63}=\frac{-140}{126}
=-1+1/9
$