x2=21

Simple and best practice solution for x2=21 equation. Check how easy it is, and learn it for the future. Our solution is simple, and easy to understand, so don`t hesitate to use it as a solution of your homework.

If it's not what You are looking for type in the equation solver your own equation and let us solve it.

Solution for x2=21 equation:



x2=21
We move all terms to the left:
x2-(21)=0
We add all the numbers together, and all the variables
x^2-21=0
a = 1; b = 0; c = -21;
Δ = b2-4ac
Δ = 02-4·1·(-21)
Δ = 84
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:
$\sqrt{\Delta}=\sqrt{84}=\sqrt{4*21}=\sqrt{4}*\sqrt{21}=2\sqrt{21}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-2\sqrt{21}}{2*1}=\frac{0-2\sqrt{21}}{2} =-\frac{2\sqrt{21}}{2} =-\sqrt{21} $
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+2\sqrt{21}}{2*1}=\frac{0+2\sqrt{21}}{2} =\frac{2\sqrt{21}}{2} =\sqrt{21} $

See similar equations:

| 6x–3x+4–2x=5x+1 | | -6+2v=v-6 | | -15-4t=17 | | -7u+16=6(u+7) | | (x-46)+1/2x+(x-35)+x=360 | | (n+8)+(n+-12)=2n+-4 | | 9x-4+8x-10=18x-2 | | -b^2+b+30=0 | | 4(x-1.50)+2x=30 | | 3(2x-5)-4x=2(x-3)-9 | | x6−15=730 | | -x/4+(-9.8)=-5.6 | | 10=6b-6 | | 12+8k=-140 | | 0.75n+16=2-0.125 | | 9x-4+8x+0=18x-2 | | 6(x−1)=30 | | x-3/5x=4 | | 9-5n=29 | | -8w+3(w-3)=1 | | 2/3x+5=27 | | 3x=(2x+40) | | 4(3n+4)=8(4n+8)+6 | | 5/8x-3/8=4/8x+7/8 | | Y=-7x+224 | | 1/8y-6=-12 | | -136=8+8x | | n=60+15+12+95 | | 4x+1=5+2(2x-4 | | 13-3p=-5(3+20) | | 4=2v-4v | | j/2​+7=12 |

Equations solver categories