64.2k views
4 votes
What is the radius of the circle given by the equation below?

x2 + 12x + y2 - 12y = -56
A. 2
B. 16
C. 4
D. 8

User Capcom
by
7.2k points

1 Answer

3 votes

Answer:

C

Explanation:

First, you gotta complete the square!

x^2+12x+36 = (x+6)^2

y^2-12y+36 = (y-6)^2

So, we have (x+12)^2 + (y-6)^2 = -56 + 36 + 36

The right side of the equation is the radius^2.

Simplify:

-56 + 36 + 36 = 16

The square root of 16 is 4, so the answer is C!

User Kiryl Plyashkevich
by
7.5k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.