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Functions and Notation
Example 12

Example 12: Function Evaluation

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

Problem

If f(x)=−4x+6, find f(−5)\text{If }f(x)=-4x+6\text{, find }f(-5)

1. Recognize Pattern

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

2. Apply Method

f(x)=1x+0,  f(5)=5f(x)=1x+0,\;f(5)=5

3. Conclude

f(−5)=−4(−5)+6=26f(-5)=-4(-5)+6=26

Final answer

f(−5)=−4(−5)+6=26f(-5)=-4(-5)+6=26
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