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Beginning and Intermediate Algebra - Wallace Math Courses ...

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Example 524.<br />

Are f(x)=<br />

3√<br />

3x +4 <strong>and</strong> g(x) = x3 −4<br />

inverses? Caculate composition<br />

3<br />

f(g(x)) Replace g(x) with x3 − 4<br />

� � � �3<br />

3 3 x − 4<br />

x − 4<br />

f<br />

Substitute for variable in f<br />

3<br />

3<br />

� � �<br />

3<br />

3 x − 4<br />

3 +4 Divide out the 3<br />

3<br />

′ s<br />

x3 3√<br />

− 4+4 Combine like terms<br />

x3 3√<br />

Take cubed root<br />

Example 525.<br />

x Simplified to x!<br />

Yes, they are inverses! Our Solution<br />

Are h(x) =2x +5<strong>and</strong> g(x)= x<br />

− 5 inverses?<br />

2<br />

h(g(x))<br />

�<br />

x<br />

�<br />

h − 5<br />

� 2<br />

x<br />

�<br />

2 − 5 +5<br />

2<br />

Calculate composition<br />

�<br />

x<br />

�<br />

Replace g(x) with − 5<br />

� 2<br />

x<br />

�<br />

Substitute − 5 for variable inh<br />

2<br />

Distrubte 2<br />

x − 10 +5 Combine like terms<br />

Example 526.<br />

Are f(x) =<br />

x − 5 Did not simplify to x<br />

No, they are not inverses Our Solution<br />

3x −2 x +2<br />

<strong>and</strong> g(x) = inverses? Calculate composition<br />

4x +1 3 − 4x � �<br />

x +2<br />

f(g(x)) Replace g(x) with<br />

3 − 4x<br />

� � � �<br />

x +2<br />

x + 2<br />

f<br />

Substitute for variable in f<br />

3 − 4x<br />

3 − 4x<br />

�<br />

x + 2<br />

3<br />

4<br />

3 − 4x<br />

�<br />

x + 2<br />

3 − 4x<br />

�<br />

− 2<br />

�<br />

+ 1<br />

402<br />

Distribute3<strong>and</strong> 4 into numerators

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