r^2-4=21

Simple and best practice solution for r^2-4=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 r^2-4=21 equation: 


Simplifying
r2 + -4 = 21

Reorder the terms:
-4 + r2 = 21

Solving
-4 + r2 = 21

Solving for variable 'r'.

Move all terms containing r to the left, all other terms to the right.

Add '4' to each side of the equation.
-4 + 4 + r2 = 21 + 4

Combine like terms: -4 + 4 = 0
0 + r2 = 21 + 4
r2 = 21 + 4

Combine like terms: 21 + 4 = 25
r2 = 25

Simplifying
r2 = 25

Take the square root of each side:
r = {-5, 5}

See similar equations:

| 5r+4=7+1+2r+5 | | 5(5t-7)=6(6t-8) | | 5x+3.6=4x+3.7 | | (x+2)(x-5)=(x-1)(x-3) | | 4(3)-4=2(3)+14 | | -8(p-1)= | | 5a^2+29a+36=0 | | 4x+3.0=2x+4.4 | | 4x-8+x=8 | | 5/72+68/90=x | | -10x+9x= | | -2.5(y-6)=-4.5 | | -9x-2.3=8x-1.7 | | 2.5m=-5.1 | | 4(3-x)-(6x+9)=-12x | | 54+9x=38+13x | | 3x+1=1+4x | | x^2+6=3 | | 850-9.8=45.0 | | 2x+5x=200+3x | | -5+a+4= | | 2n^2+20n+48=0 | | 2x-8=x-5 | | 2x+2x+6=24 | | 3(-11)-2(-11+6)=4(-11)-(-11-10) | | 20-3y=2y | | 5(z+6)=40 | | k^2-15=2k | | 2+5p=5p+2 | | -5((x-2)(x-2))=-5(x-2)(x+4) | | -6(-2+2x)=-6x+30 | | -2=11x-24 |

Equations solver categories