(4x-3)(-7x+7)=0

Solution for (4x-3)(-7x+7)=0 equation:

(4x-3)(-7x+7)=0

We multiply parentheses ..

(-28x^2+28x+21x-21)=0

We get rid of parentheses

-28x^2+28x+21x-21=0

We add all the numbers together, and all the variables

-28x^2+49x-21=0

a = -28; b = 49; c = -21;
Δ = b2-4ac
Δ = 492-4·(-28)·(-21)
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(49)-7}{2*-28}=\frac{-56}{-56}
=1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(49)+7}{2*-28}=\frac{-42}{-56}
=3/4
$