tolong dijawab pliss

f(1) = 6
a(1)³- b(1) + 8 = 6
a - b = 6 - 8
a - b = -2 (persamaan 1)
f(2) = 16
a(2)³ - b(2) + 8 = 16
8a - 2b = 8 |÷2| ---> 4a - b = 4 (pers 2)
eliminasi
a - b = -2
4a-b = 4
------------- _
-3a = -6
a = -6/-3 = 2
a - b = -2
2 - b = -2
2 + 2 = b
b = 4

f(x) = 2x³ - 4x + 8
f(-1) = 2(-1)³ - 4(-1) + 8
= -2 + 4 + 8 = 10