(1-7x)(1+9x)=0

Solution for (1-7x)(1+9x)=0 equation:

(1-7x)(1+9x)=0

We add all the numbers together, and all the variables

(-7x+1)(9x+1)=0

We multiply parentheses ..

(-63x^2-7x+9x+1)=0

We get rid of parentheses

-63x^2-7x+9x+1=0

We add all the numbers together, and all the variables

-63x^2+2x+1=0

a = -63; b = 2; c = +1;
Δ = b2-4ac
Δ = 22-4·(-63)·1
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-16}{2*-63}=\frac{-18}{-126}
=1/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+16}{2*-63}=\frac{14}{-126}
=-1/9
$