Chapter 13 - Section 13.3 - Tangent Lines and Derivatives - 13.3 Exercises - Page 922: 27

$f’\left( x\right) =2x+2$ $f’\left( 3\right) =8$ $f’( 4)=10 $

$f\left( x\right) =x^{2}+2x\Rightarrow f'\left( x\right) =2\times x^{2-1}+2\times 1\times x^{1-1}=2x+2\times x^{0}=2x+2\Rightarrow $ $f’^{}\left( 3\right) =2\times 3+2=8$ $f’^{}\left( 4\right) =2\times 4+2=10$