3x^2+x=21/2

Solution for 3x^2+x=21/2 equation:

3x^2+x=21/2

We move all terms to the left:

3x^2+x-(21/2)=0

We add all the numbers together, and all the variables

3x^2+x-(+21/2)=0

We get rid of parentheses

3x^2+x-21/2=0

We multiply all the terms by the denominator


3x^2*2+x*2-21=0

Wy multiply elements

6x^2+2x-21=0

a = 6; b = 2; c = -21;
Δ = b2-4ac
Δ = 22-4·6·(-21)
Δ = 508
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{508}=\sqrt{4*127}=\sqrt{4}*\sqrt{127}=2\sqrt{127}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-2\sqrt{127}}{2*6}=\frac{-2-2\sqrt{127}}{12}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+2\sqrt{127}}{2*6}=\frac{-2+2\sqrt{127}}{12}
$