r^2+4r-42=0

Simple and best practice solution for r^2+4r-42=0 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+4r-42=0 equation:


Simplifying
r2 + 4r + -42 = 0

Reorder the terms:
-42 + 4r + r2 = 0

Solving
-42 + 4r + r2 = 0

Solving for variable 'r'.

Begin completing the square.

Move the constant term to the right:

Add '42' to each side of the equation.
-42 + 4r + 42 + r2 = 0 + 42

Reorder the terms:
-42 + 42 + 4r + r2 = 0 + 42

Combine like terms: -42 + 42 = 0
0 + 4r + r2 = 0 + 42
4r + r2 = 0 + 42

Combine like terms: 0 + 42 = 42
4r + r2 = 42

The r term is 4r.  Take half its coefficient (2).
Square it (4) and add it to both sides.

Add '4' to each side of the equation.
4r + 4 + r2 = 42 + 4

Reorder the terms:
4 + 4r + r2 = 42 + 4

Combine like terms: 42 + 4 = 46
4 + 4r + r2 = 46

Factor a perfect square on the left side:
(r + 2)(r + 2) = 46

Calculate the square root of the right side: 6.782329983

Break this problem into two subproblems by setting 
(r + 2) equal to 6.782329983 and -6.782329983.

Subproblem 1

r + 2 = 6.782329983 Simplifying r + 2 = 6.782329983 Reorder the terms: 2 + r = 6.782329983 Solving 2 + r = 6.782329983 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-2' to each side of the equation. 2 + -2 + r = 6.782329983 + -2 Combine like terms: 2 + -2 = 0 0 + r = 6.782329983 + -2 r = 6.782329983 + -2 Combine like terms: 6.782329983 + -2 = 4.782329983 r = 4.782329983 Simplifying r = 4.782329983

Subproblem 2

r + 2 = -6.782329983 Simplifying r + 2 = -6.782329983 Reorder the terms: 2 + r = -6.782329983 Solving 2 + r = -6.782329983 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-2' to each side of the equation. 2 + -2 + r = -6.782329983 + -2 Combine like terms: 2 + -2 = 0 0 + r = -6.782329983 + -2 r = -6.782329983 + -2 Combine like terms: -6.782329983 + -2 = -8.782329983 r = -8.782329983 Simplifying r = -8.782329983

Solution

The solution to the problem is based on the solutions from the subproblems. r = {4.782329983, -8.782329983}

See similar equations:

| 13/9X3-(5-3) | | -12x+2y=10 | | 0.07(4t-5)=0.28(t+2)-0.91 | | 0.50x+0.15(30)=38.5 | | 80c^2+52c+-60=0 | | 1/2x-1/3(x-6)=3x | | ((9x^2-4)(9x^2+4))/((3x+2)(1.5x-1))=0 | | 30=2x/-5x | | 72/3 | | 6-4(x+4)=8x-2(3x+5) | | =-1x+5 | | 21a/56a | | 9(t-5)+3t=4(3t+4)-9 | | =-6x+15 | | 30/36 | | 177*44/59*8/9 | | 8/x=2/3 | | 4/x=23/8x+3 | | (2x+3)=13-x | | -(6y+2)-(-5y-7)=-2 | | 57=(1576)(23/180)r | | -(4y+2)-(-3y-7)=1 | | 3/x=9/(5x)+2 | | 57=(9062/45)r | | 3+x=10-(.166x) | | -1/16(x-18)+1/2(x+2)=x+4 | | simplyx=5+2y | | 96=(3x+1)(x+1) | | -2(2c-4)=0.34(-12c+24) | | 5x-10y=25 | | 32+4X=240 | | 18(10-.75y)+6y=120 |

Equations solver categories