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Functions and Notation
Example 10

Example 10: Function Evaluation

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

Problem

If f(x)=−3x−4, find f(4)\text{If }f(x)=-3x-4\text{, find }f(4)

1. Recognize Pattern

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

2. Apply Method

f(x)=−5x+4,  f(5)=−21f(x)=-5x+4,\;f(5)=-21

3. Conclude

f(4)=−3(4)−4=−16f(4)=-3(4)-4=-16

Final answer

f(4)=−3(4)−4=−16f(4)=-3(4)-4=-16
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