What are the solutions to the system of equations?

Question

x² + y² = 5

y = 2x

Answer 1

x² + y² = 5
y = 2x

 

Since y = 2x, substitute 2x in place of y in the first equation:

 

x² + y² = 5

x² + (2x)² = 5

x² + 4x² = 5

5x² = 5

 

Can you finish it from here?  There are two answers