Math lovers of the world! -Please complete this equation for me, step by step.. Much thanks :)
π(r+6) ² = 15(2πr) + 2 πr²
~Michelle
First, recognize that since everything on both sides of the equal is being multiplied by π, it can be factored out of the equation entirely.
π(r+6) ² = π[15(2r) + 2r²]
(r+6) ² = [15(2r) + 2r²]
>> multiply out the parenthetical expressions
(r² + 12r + 36) = 30r + 2r²
r² + 12r + 36 = 30r + 2r²
>> move everything to one side of the equal sign
0 = r² + 18r - 36
>> solve for r using the quadratic formula
r = (1/2)[-18 ± √(324+144)]
>> simplify using rules of algebra for radicals
r = (1/2)(-18) ± (1/2)√(468)
r = -9 ± (1/2)√468
r = -9 ± (1/2)√(36*13)
r = -9 ± (1/2)(6)√13
r = -9 ± 3√13
ANSWER
r = -9 + 3√13
r = -9 - 3√13
The Ï is just a distraction.
Those answers check out ok in Microsoft Excel
It looks like it's going to be a weird quadratic equation.
ugh.
Lose the Ï and work from there.
Copyright © 2024 1QUIZZ.COM - All rights reserved.
Answers & Comments
Verified answer
π(r+6) ² = 15(2πr) + 2 πr²
First, recognize that since everything on both sides of the equal is being multiplied by π, it can be factored out of the equation entirely.
π(r+6) ² = 15(2πr) + 2 πr²
π(r+6) ² = π[15(2r) + 2r²]
(r+6) ² = [15(2r) + 2r²]
>> multiply out the parenthetical expressions
(r² + 12r + 36) = 30r + 2r²
r² + 12r + 36 = 30r + 2r²
>> move everything to one side of the equal sign
0 = r² + 18r - 36
>> solve for r using the quadratic formula
r = (1/2)[-18 ± √(324+144)]
>> simplify using rules of algebra for radicals
r = (1/2)(-18) ± (1/2)√(468)
r = -9 ± (1/2)√468
r = -9 ± (1/2)√(36*13)
r = -9 ± (1/2)(6)√13
r = -9 ± 3√13
ANSWER
r = -9 + 3√13
r = -9 - 3√13
The Ï is just a distraction.
Those answers check out ok in Microsoft Excel
It looks like it's going to be a weird quadratic equation.
ugh.
Lose the Ï and work from there.