Question

Which of the following points lies on the circle whose center is at the origin and whose radius is 5?

A.) (-3, 4)

B.) (1, -2)

C.) (√5,√5 )

Answer 1

the equation of a circle centered at the origin with radius of r is
\[x^2+y^2=r^2\]
This circle's equation is
\[x^2+y^2=5\]
Which of the points makes that equation true?

Answer 2

you actually have to plug the numbers in to find the answer

Answer 3

i think i am doing it wrong

Answer 4

what did you get for x² + y² when you put in (-3, 4)?

Answer 5

25

Answer 6

ok. that's not 5, so (-3,4) isn't the answer.
Try (1, -2)

Answer 7

5

Answer 8

right. so (1, -2) is the answer since it gives 5 on the left to match the 5 on the right