tolong dibntu ya. ntar jam 7.30 uda mau ujian. ini kisi-kisi yang masih saya ga bs jwb

15) y = ax^2 + bx + 2
(2, 0) => 0 = a(2)^2 + b(2) + 2
=> 4a + 2b + 2 = 0
=> 2a + b + 1 = 0
=> 2a + b = -1

y = -3x + 6 => m = -3
m = y'
y' = 2ax + b
m = 2a(2) + b = -3
=> 4a + b = -3

Eliminasi
4a + b = -3
2a + b = -1
--------------- --
2a = -2 => a = -1

2a + b = -1
2(-1) + b = -1
b = 1

16) f(x) = 2x^3 - 9x^2 + 12x turun jika f'(x) < 0
f'(x) = 6x^2 - 18x + 12 < 0
=> x^2 - 3x + 2 < 0
=> (x - 1)(x - 2) < 0
=> x = 1 atau x = 2
Garis bilangan
+++ (1) --- (2) +++
1 < x < 2