3x*2x+7=21

Solution for 3x*2x+7=21 equation:

3x*2x+7=21

We move all terms to the left:

3x*2x+7-(21)=0

We add all the numbers together, and all the variables

3x*2x-14=0

Wy multiply elements

6x^2-14=0

a = 6; b = 0; c = -14;
Δ = b2-4ac
Δ = 02-4·6·(-14)
Δ = 336
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:

$\sqrt{\Delta}=\sqrt{336}=\sqrt{16*21}=\sqrt{16}*\sqrt{21}=4\sqrt{21}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-4\sqrt{21}}{2*6}=\frac{0-4\sqrt{21}}{12}
=-\frac{4\sqrt{21}}{12}
=-\frac{\sqrt{21}}{3}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+4\sqrt{21}}{2*6}=\frac{0+4\sqrt{21}}{12}
=\frac{4\sqrt{21}}{12}
=\frac{\sqrt{21}}{3}
$