r^2-30r+20=0

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Solution for r^2-30r+20=0 equation:


Simplifying
r2 + -30r + 20 = 0

Reorder the terms:
20 + -30r + r2 = 0

Solving
20 + -30r + r2 = 0

Solving for variable 'r'.

Begin completing the square.

Move the constant term to the right:

Add '-20' to each side of the equation.
20 + -30r + -20 + r2 = 0 + -20

Reorder the terms:
20 + -20 + -30r + r2 = 0 + -20

Combine like terms: 20 + -20 = 0
0 + -30r + r2 = 0 + -20
-30r + r2 = 0 + -20

Combine like terms: 0 + -20 = -20
-30r + r2 = -20

The r term is -30r.  Take half its coefficient (-15).
Square it (225) and add it to both sides.

Add '225' to each side of the equation.
-30r + 225 + r2 = -20 + 225

Reorder the terms:
225 + -30r + r2 = -20 + 225

Combine like terms: -20 + 225 = 205
225 + -30r + r2 = 205

Factor a perfect square on the left side:
(r + -15)(r + -15) = 205

Calculate the square root of the right side: 14.317821063

Break this problem into two subproblems by setting 
(r + -15) equal to 14.317821063 and -14.317821063.

Subproblem 1

r + -15 = 14.317821063 Simplifying r + -15 = 14.317821063 Reorder the terms: -15 + r = 14.317821063 Solving -15 + r = 14.317821063 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '15' to each side of the equation. -15 + 15 + r = 14.317821063 + 15 Combine like terms: -15 + 15 = 0 0 + r = 14.317821063 + 15 r = 14.317821063 + 15 Combine like terms: 14.317821063 + 15 = 29.317821063 r = 29.317821063 Simplifying r = 29.317821063

Subproblem 2

r + -15 = -14.317821063 Simplifying r + -15 = -14.317821063 Reorder the terms: -15 + r = -14.317821063 Solving -15 + r = -14.317821063 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '15' to each side of the equation. -15 + 15 + r = -14.317821063 + 15 Combine like terms: -15 + 15 = 0 0 + r = -14.317821063 + 15 r = -14.317821063 + 15 Combine like terms: -14.317821063 + 15 = 0.682178937 r = 0.682178937 Simplifying r = 0.682178937

Solution

The solution to the problem is based on the solutions from the subproblems. r = {29.317821063, 0.682178937}

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