Question

What are the solutions of the following system x2+y2=25 , 2x+y=-5

Answer 1

y=5-2x
x^2 + (5-2x)^2 = 25

x^2 + 25-20x+4x^2 = 25

x^2 +4x^2-20x+25=25
5x^2 -20x=0

x=0 and y=5

Answer 2

x^2+y^2=25

2x+y=-5

(0, -5) plug into equation 1 and 2 but you have to find what second ordered pair fills in for x^2+y^2=25 which would be (-4, 3). Reasoning is that-

-4^2=16 and 3^2=9 so 16+9=25

The Correct answer is C (0, -5) and (-4, 3)