7x(x+4.9)=56

Solution for 7x(x+4.9)=56 equation:

7x(x+4.9)=56

We move all terms to the left:

7x(x+4.9)-(56)=0

We multiply parentheses

7x^2+34.3x-56=0

a = 7; b = 34.3; c = -56;
Δ = b2-4ac
Δ = 34.32-4·7·(-56)
Δ = 2744.49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(34.3)-\sqrt{2744.49}}{2*7}=\frac{-34.3-\sqrt{2744.49}}{14}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(34.3)+\sqrt{2744.49}}{2*7}=\frac{-34.3+\sqrt{2744.49}}{14}
$