x2/4x-21=0

Solution for x2/4x-21=0 equation:

x2/4x-21=0


Domain of the equation: 4x!=0

x!=0/4

x!=0

x∈R


We multiply all the terms by the denominator


x2-21*4x=0

We add all the numbers together, and all the variables

x^2-21*4x=0

Wy multiply elements

x^2-84x=0

a = 1; b = -84; c = 0;
Δ = b2-4ac
Δ = -842-4·1·0
Δ = 7056
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{7056}=84$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-84)-84}{2*1}=\frac{0}{2}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-84)+84}{2*1}=\frac{168}{2}
=84
$