89.7k views
0 votes
X^2-18x=-72

I need two solutions. Thanks.

User Rarp
by
5.5k points

2 Answers

3 votes

Answer:

ans is x=12 or x=6

same as other but a different way to do it

Explanation:

x^2-18x=-72

x^2-2*9x=-72

completing square x^2-2*9x+9^2=-72+9^2

(x-9)^2=-72+81=9

taking square root n add a +/- on left

(x-9) = +/-3

x-9 = 3 or x-9 = -3

x=12 or x=6


User Wouter Verhelst
by
5.4k points
5 votes

Hey Astute!

Solve: x^2 - 18x = -72

Solution:

x^2 − 18x − (−72) = −72 − (−72) (Subtract -72 from both sides of the equation)

x^2 − 18x + 72 = 0

(x − 6) (x − 12) = 0 (Factor left side)

x − 6 = 0 or x − 12 = 0 (factors have to equal 0)

6 - 6 = 0 or 12 - 12 = 0

Answer:

x = 6 or x = 12

Hope This Helps, Have a Great Day!

User Ryan Tsui
by
5.1k points