621.72=6.28r^2+6.28r(18.1)

Simple and best practice solution for 621.72=6.28r^2+6.28r(18.1) 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 621.72=6.28r^2+6.28r(18.1) equation:


Simplifying
621.72 = 6.28r2 + 6.28r(18.1)

Reorder the terms for easier multiplication:
621.72 = 6.28r2 + 6.28 * 18.1r

Multiply 6.28 * 18.1
621.72 = 6.28r2 + 113.668r

Reorder the terms:
621.72 = 113.668r + 6.28r2

Solving
621.72 = 113.668r + 6.28r2

Solving for variable 'r'.

Reorder the terms:
621.72 + -113.668r + -6.28r2 = 113.668r + -113.668r + 6.28r2 + -6.28r2

Combine like terms: 113.668r + -113.668r = 0.000
621.72 + -113.668r + -6.28r2 = 0.000 + 6.28r2 + -6.28r2
621.72 + -113.668r + -6.28r2 = 6.28r2 + -6.28r2

Combine like terms: 6.28r2 + -6.28r2 = 0.00
621.72 + -113.668r + -6.28r2 = 0.00

Begin completing the square.  Divide all terms by
-6.28 the coefficient of the squared term: 

Divide each side by '-6.28'.
-99 + 18.1r + r2 = 0

Move the constant term to the right:

Add '99' to each side of the equation.
-99 + 18.1r + 99 + r2 = 0 + 99

Reorder the terms:
-99 + 99 + 18.1r + r2 = 0 + 99

Combine like terms: -99 + 99 = 0
0 + 18.1r + r2 = 0 + 99
18.1r + r2 = 0 + 99

Combine like terms: 0 + 99 = 99
18.1r + r2 = 99

The r term is 18.1r.  Take half its coefficient (9.05).
Square it (81.9025) and add it to both sides.

Add '81.9025' to each side of the equation.
18.1r + 81.9025 + r2 = 99 + 81.9025

Reorder the terms:
81.9025 + 18.1r + r2 = 99 + 81.9025

Combine like terms: 99 + 81.9025 = 180.9025
81.9025 + 18.1r + r2 = 180.9025

Factor a perfect square on the left side:
(r + 9.05)(r + 9.05) = 180.9025

Calculate the square root of the right side: 13.45

Break this problem into two subproblems by setting 
(r + 9.05) equal to 13.45 and -13.45.

Subproblem 1

r + 9.05 = 13.45 Simplifying r + 9.05 = 13.45 Reorder the terms: 9.05 + r = 13.45 Solving 9.05 + r = 13.45 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-9.05' to each side of the equation. 9.05 + -9.05 + r = 13.45 + -9.05 Combine like terms: 9.05 + -9.05 = 0.00 0.00 + r = 13.45 + -9.05 r = 13.45 + -9.05 Combine like terms: 13.45 + -9.05 = 4.4 r = 4.4 Simplifying r = 4.4

Subproblem 2

r + 9.05 = -13.45 Simplifying r + 9.05 = -13.45 Reorder the terms: 9.05 + r = -13.45 Solving 9.05 + r = -13.45 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-9.05' to each side of the equation. 9.05 + -9.05 + r = -13.45 + -9.05 Combine like terms: 9.05 + -9.05 = 0.00 0.00 + r = -13.45 + -9.05 r = -13.45 + -9.05 Combine like terms: -13.45 + -9.05 = -22.5 r = -22.5 Simplifying r = -22.5

Solution

The solution to the problem is based on the solutions from the subproblems. r = {4.4, -22.5}

See similar equations:

| 17+11b=-5(-4b+20) | | 16y= | | 14=-2(u+1) | | 3(2(0.3)-5)+31=14 | | 5g-10-12=15g+8(-2g+10) | | 4(5x+2)=10(2x+1) | | 10x-41=6x-5 | | 3x-2(5-4(2x-(1-x)))=36 | | 41=4v+1 | | 1.2*75=90 | | 14.08+1.7n=0.6n | | 2x-4(6x-4(x+1))=2(3x+5) | | 3(14x-15)= | | -16+2h=9(8h+4) | | -6+2y=10 | | 2(x+3(x-1))=7x-1 | | -10.32+14.89+2d=15.77+2.7d | | 11=7(7+(5+x)) | | 25x^3-100x^2+4=x | | 6(7+2(k-1))-1=5 | | -3(u+7)=-6 | | 5(2x+2)=5(3x+3) | | 5x+4x-7x=14-11+7 | | 4(3+2(x+5))=76 | | 20=2-3x | | -12.87+15.9s=-11.97+16.4s | | 4c+28=6x | | 2.9w=5+4.7w-7.6 | | (x+y)(x-y)=180 | | 3m+2117=6352 | | -20+7x=-2(-8x-6-5x) | | 5y+6x=23 |

Equations solver categories