Question

Need help.
Find the derivative of f(x) = 5x + 9 at x = 2.
Find the derivative of f(x) = 6 divided by x at x = -2.

Thanks

Answer 1

$f(x)=5x+9\\ f'(x)=5$
The derivative is constant. It's equal 5 for any argument.

$f(x)=\dfrac{6}{x}\\ f'(x)=-\dfrac{6}{x^2}\\ f'(-2)=-\dfrac{6}{(-2)^2}=-\dfrac{6}{4}=-\dfrac{3}{2}$