Question

Solve the system, 4x^2 + y^2 = 20 and y = 4x.

(square root of 10/2, 2 square root of 10)?

Answer 1

Hmmm. I get (-1,-4) and (1,4)
y=4x, so
4x^2 + (4x)^2 = 20
4x^2 + 16x^2 = 20
20x^2 = 20
x = ±1
so y=±4

Answer 2

Thank you