4.9(x^2-8x+16)-4.9(16)=0

Solution for 4.9(x^2-8x+16)-4.9(16)=0 equation:

4.9(x^2-8x+16)-4.9(16)=0

We multiply parentheses

4.9x^2-39.2x+78.4-4.916=0

We add all the numbers together, and all the variables

4.9x^2-39.2x+73.484=0

a = 4.9; b = -39.2; c = +73.484;
Δ = b2-4ac
Δ = -39.22-4·4.9·73.484
Δ = 96.3536
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-39.2)-\sqrt{96.3536}}{2*4.9}=\frac{39.2-\sqrt{96.3536}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-39.2)+\sqrt{96.3536}}{2*4.9}=\frac{39.2+\sqrt{96.3536}}{9.8}
$