Suku banyak f(x)=ax³+15x²+33x+b habis dibagi dengan (x²+5x+4) maka nilai a dan b berturut

x² + 5x + 4 = 0
(x + 4)(x + 1) = 0
x + 4 = 0
x = -4
f(-4) = a(-4)³ + 15(-4)² + 33(-4) + b = 0
-64a + 240 - 132 + b = 0
-64a + b + 108 = 0
-64a + b = -108
x + 1 = 0
x = -1
f(-1) = a(-1)³ + 15(-1)² + 33(-1) + b = 0
-a + 15 - 33 + b = 0
-a + b - 18 = 0
-a + b = 18
eliminasi
-64a + b = -108
- a + b = 18
----------------------- _
- 63a = -126
a = -126/-63 = 2
-a + b = 18
-2 + b = 18
b = 20