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Functions and Notation
Example 7

Example 7: Function Evaluation

Step-by-step worked example for this lesson track.

Problem

If f(x)=3x−5, find f(−1)\text{If }f(x)=3x-5\text{, find }f(-1)

1. Recognize Pattern

f(x)=ax+b⇒f(k)=ak+bf(x)=ax+b\Rightarrow f(k)=ak+b

2. Apply Method

f(x)=−6x−4,  f(−5)=26f(x)=-6x-4,\;f(-5)=26

3. Conclude

f(−1)=3(−1)−5=−8f(-1)=3(-1)-5=-8

Final answer

f(−1)=3(−1)−5=−8f(-1)=3(-1)-5=-8
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