7x^2+21x^2+14x=0

Solution for 7x^2+21x^2+14x=0 equation:

7x^2+21x^2+14x=0

We add all the numbers together, and all the variables

28x^2+14x=0

a = 28; b = 14; c = 0;
Δ = b2-4ac
Δ = 142-4·28·0
Δ = 196
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{196}=14$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(14)-14}{2*28}=\frac{-28}{56}
=-1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(14)+14}{2*28}=\frac{0}{56}
=0
$