Question

Q.
[tex]Jika\:f(x)=2x+b\:dan\:f^{-1}(9)=3,maka\:nilai\:f(f(3))\: adalah...[/tex]
A.6
B.9
C.12
D.18
E.21​

Answer 1

Verified answer

Jawaban:

E. 21

Penjelasan dengan langkah-langkah:

[tex]f(x) = 2x + b[/tex]

[tex]y = 2x + b[/tex]

[tex]2x = y - b[/tex]

[tex]x = \frac{y - b}{2} [/tex]

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[tex]f^{ - 1}(x) = \frac{x - b}{2} [/tex]

[tex]f^{ - 1}(9) = 3<==>9 - b = 6<==>b = 3[/tex]

[tex]f(x) = 2x + 3[/tex]

[tex]f(3) = 2(3) + 3 = 6 + 3 = 9[/tex]

[tex]f(f(3)) = 2(9) + 3 = 18 + 3 = 21 \: (E.)[/tex]

Kesimpulan :

E. 21

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