0=-4.9x^2+40x-7

Solution for 0=-4.9x^2+40x-7 equation:

0=-4.9x^2+40x-7

We move all terms to the left:

0-(-4.9x^2+40x-7)=0

We add all the numbers together, and all the variables

-(-4.9x^2+40x-7)=0

We get rid of parentheses

4.9x^2-40x+7=0

a = 4.9; b = -40; c = +7;
Δ = b2-4ac
Δ = -402-4·4.9·7
Δ = 1462.8
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{-(-40)-\sqrt{1462.8}}{2*4.9}=\frac{40-\sqrt{1462.8}}{9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-40)+\sqrt{1462.8}}{2*4.9}=\frac{40+\sqrt{1462.8}}{9.8}
$