• 올인원 · 1117418 · 24/12/20 07:29 · MS 2021

    f(0) = 0, f(4) = 7, f'(4) = 0
    구간 [0, 4)에서 f(x)는 증가
    -> f(x) = -a(x - 4)²(x + 7/(16a)) + 7

    f(-2) = -36a(7/(16a) - 2) + 7
    = -35/4  + 72a,
    4f(-2) = 288a - 35

    f(7) = -9a(7 + 7/(16a)) + 7 < 0
    = 49/16 - 63a < 0,
    63a > 49/16, 288a > 14
    f'(0) = -16a + 7/2 >= 0,
    16a <= 7/2, 288a <= 63
    --> 14 < 288a <= 63,
    -21 < 4f(-2) <= 28

    최솟값 -20, 최댓값 28
    더하면 8