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1. Find f(x) if it is known that f(x+5)=x+12.

2. Find f(x) if it is known that f(x−5)=1.2x−6.

1 Answer

7 votes

Answer:

1. f(x)=x+7

2. f(x)=1.2x

Explanation:

1. If f(x+5)=x+12, then substitute


t=x+5\Rightarrow x=t-5

Hence,


f(t)=(t-5)+12\\ \\f(t)=t+7

Now change t into x:


f(x)=x+7

2. If f(x-5)=1.2x-6, then substitute


t=x-5\Rightarrow x=t+5

Hence,


f(t)=1.2(t+5)-6\\ \\f(t)=1.2t+6-6\\ \\f(t)=1.2t

Now change t into x:


f(x)=1.2x

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