(4-9x)(7-4x)=0

Solution for (4-9x)(7-4x)=0 equation:

(4-9x)(7-4x)=0

We add all the numbers together, and all the variables

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

We multiply parentheses ..

(+36x^2-63x-16x+28)=0

We get rid of parentheses

36x^2-63x-16x+28=0

We add all the numbers together, and all the variables

36x^2-79x+28=0

a = 36; b = -79; c = +28;
Δ = b2-4ac
Δ = -792-4·36·28
Δ = 2209
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2209}=47$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-79)-47}{2*36}=\frac{32}{72}
=4/9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-79)+47}{2*36}=\frac{126}{72}
=1+3/4
$