When is an ellipse also a circle? A. when a = b
B. when y =
C when a = 0
D. when the center is at (0,0)

Dr.cooper just started an experiment. he will collect data for 8 days. how many hours is this

John used linear combination to solve the system of equations shown. he did so by multiplying the first equation by -3 and the second equation by another number to eliminate the x-terms. what number did jonas multiply the second equation by? 4x-6y=23x+5y=11

Me. i can't figure out this question. give an explanation too. .