The maximum value of 4 sin2x + 3 cos2x is :

3 4 5 7

4

y = 4 sin2x + 3 cos2x y = sin2x + 3(sin2x + cos2x) y = sin2x + 3 since sin2x + cos2x = 1 y = sin2x + 3 we know that  0 ≤ sin2x ≤ 1 so   3 ≤ sin2x + 3 ≤ 4 so ymax = 4