Which equation is linear?

group of answer choices

latex: y=2x+2 y = 2 x + 2 y = 2 x + 2 y = 2 x + 2 y = 2 x + 2

latex: y=2x^2+2 y = 2 x 2 + 2 y = 2 x 2 + 2 y = 2 x 2 + 2 y = 2 x 2 + 2

latex: y=2x^3+2 y = 2 x 3 + 2 y = 2 x 3 + 2 y = 2 x 3 + 2 y = 2 x 3 + 2

latex: y=2x^4+2