Page 31 - Modul Ajar Matematika Fungsi Komposisi Kelas X Genap

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

Contoh 6: 4

−1
Jika f (x) = 2x x ∈ R, x ≠ dan f (k) = 1. Tentukan nilai k!
,
3x − 4 3
Penyelesaian:
Misalkan f(x) = y,
2x
y = 3x − 4
y(3x - 4) = 2x
3xy – 4y = 2x
3xy – 2x = 4y
x(3y – 2) = 4y
4 y
x =
3y-2
4x
-1
f (x) =
3x-2
4k
f (k) =
-1
3k-2
1 = 4k
3k-2
3k – 2 = 4k
k = -2

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