(2x-7)(-x-7)=0

Solution for (2x-7)(-x-7)=0 equation:

(2x-7)(-x-7)=0

We add all the numbers together, and all the variables

(2x-7)(-1x-7)=0

We multiply parentheses ..

(-2x^2-14x+7x+49)=0

We get rid of parentheses

-2x^2-14x+7x+49=0

We add all the numbers together, and all the variables

-2x^2-7x+49=0

a = -2; b = -7; c = +49;
Δ = b2-4ac
Δ = -72-4·(-2)·49
Δ = 441
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{441}=21$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-7)-21}{2*-2}=\frac{-14}{-4}
=3+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+21}{2*-2}=\frac{28}{-4}
=-7
$