Jika f(x) dibagi x-1 sisa 5 Jika f(x) dibagi x²-2x-3 sisa 2x+1 Maka jika dibagi x²-1 sisa?

Langsung aja y

x² - 1 = (x - 1)(x + 1)
x² - 2x - 3 = (x - 3)(x + 1)

f(1) = 5
f(-1) = 2(-1) + 1 = -1

cara 1
S = {f(1) - f(-1) / 1-(-1)}x + {1.f(-1) - (-1)f(1) / 1-(-1)}
S = {5-(-1) / 2}x + {1.(-1) - (-1).5 / 2}
S = (6/2)x + (4/2)
S = 3x + 2

cara 2
f(x) = ax + b

f(1) = a + b
5 = a + b

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

eliminasi
a + b = 5
-a + b = -1
________-
2a = 6
a = 3

subtitusi
a + b = 5
b = 5 - 3
b = 2

f(x) = ax + b
f(x) = 3x + 2

S = 3x + 2

Cara 1 dan Cara 2 SAMA

semoga berguna ^_^