Question

Pls Help - Calc. HW dy/dx problem

Answer 1

Answer:

$\displaystyle y' = \frac{-2}{x \ln (10)[\log (x) - 2]^2}$

General Formulas and Concepts:

Calculus

Differentiation

• Derivatives
• Derivative Notation

Derivative Property [Addition/Subtraction]:                                                         $\displaystyle \frac{d}{dx}[f(x) + g(x)] = \frac{d}{dx}[f(x)] + \frac{d}{dx}[g(x)]$

Derivative Rule [Basic Power Rule]:

1. f(x) = cxⁿ
2. f’(x) = c·nxⁿ⁻¹

Derivative Rule [Quotient Rule]:                                                                           $\displaystyle \frac{d}{dx} [\frac{f(x)}{g(x)} ]=\frac{g(x)f'(x)-g'(x)f(x)}{g^2(x)}$

Step-by-step explanation:

Step 1: Define

Identify.

$\displaystyle y = \frac{\log (x)}{\log (x) - 2}$

Step 2: Differentiate

1. [Function] Derivative Rule [Quotient Rule]:                                                 $\displaystyle y' = \frac{[\log (x) - 2][\log (x)]' - [\log (x) - 2]'[\log (x)]}{[\log (x) - 2]^2}$
2. Rewrite [Derivative Rule - Addition/Subtraction]:                                       $\displaystyle y' = \frac{[\log (x) - 2][\log (x)]' - [\log (x)' - 2'][\log (x)]}{[\log (x) - 2]^2}$
3. Logarithmic Differentiation:                                                                         $\displaystyle y' = \frac{[\log (x) - 2]\frac{1}{\ln (10)x} - [\frac{1}{\ln (10)x} - 2'][\log (x)]}{[\log (x) - 2]^2}$
4. Derivative Rule [Basic Power Rule]:                                                             $\displaystyle y' = \frac{[\log (x) - 2]\frac{1}{\ln (10)x} - \frac{1}{\ln (10)x}[\log (x)]}{[\log (x) - 2]^2}$
5. Simplify:                                                                                                         $\displaystyle y' = \frac{\frac{\log (x) - 2}{\ln (10)x} - \frac{\log (x)}{\ln (10)x}}{[\log (x) - 2]^2}$
6. Simplify:                                                                                                         $\displaystyle y' = \frac{\frac{-2}{\ln (10)x}}{[\log (x) - 2]^2}$
7. Rewrite:                                                                                                         $\displaystyle y' = \frac{-2}{x \ln (10)[\log (x) - 2]^2}$

Topic: AP Calculus AB/BC (Calculus I/I + II)

Unit: Differentiation