x(7x-49)=0

Solution for x(7x-49)=0 equation:

x(7x-49)=0

We multiply parentheses

7x^2-49x=0

a = 7; b = -49; c = 0;
Δ = b2-4ac
Δ = -492-4·7·0
Δ = 2401
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2401}=49$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-49)-49}{2*7}=\frac{0}{14}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-49)+49}{2*7}=\frac{98}{14}
=7
$