Question

Difficulty: MediumDifferentiation of Trigonometric, Exponential, and Logarithmic Functions

If y=e2xtanxy = e^{2x} \tan x, what is dydx\frac{dy}{dx}?

  1. e2x(2tanx+sec2x)e^{2x}(2\tan x + \sec^2 x)Answer
  2. B
    e2x(tanx+sec2x)e^{2x}(\tan x + \sec^2 x)
  3. C
    e2x(2tanxsec2x)e^{2x}(2\tan x - \sec^2 x)
  4. D
    2e2xsec2x2e^{2x} \sec^2 x

Answer

e2x(2tanx+sec2x)e^{2x}(2\tan x + \sec^2 x)
Applying the product rule ddx[uv]=uv+uv\frac{d}{dx}[uv] = u'v + uv' with u=e2xu = e^{2x} and v=tanxv = \tan x gives u=2e2xu' = 2e^{2x} and v=sec2xv' = \sec^2 x. Substituting these into the formula yields 2e2xtanx+e2xsec2x=e2x(2tanx+sec2x)2e^{2x}\tan x + e^{2x}\sec^2 x = e^{2x}(2\tan x + \sec^2 x).

Step-by-Step Solution

1
Identify the component functions for the product rule
Let u(x)=e2xu(x) = e^{2x} and v(x)=tanxv(x) = \tan x.
The given function y=e2xtanxy = e^{2x} \tan x is a product of two functions.
2
Differentiate each component function separately
dudx=2e2x\frac{du}{dx} = 2e^{2x} by the chain rule, and dvdx=sec2x\frac{dv}{dx} = \sec^2 x.
The derivative of ekxe^{kx} is kekxk e^{kx} and the derivative of tanx\tan x is sec2x\sec^2 x.
3
Apply the product rule formula dydx=udvdx+vdudx\frac{dy}{dx} = u \frac{dv}{dx} + v \frac{du}{dx}
dydx=e2xsec2x+tanx2e2x\frac{dy}{dx} = e^{2x} \cdot \sec^2 x + \tan x \cdot 2e^{2x}.
Combining the terms according to the standard product rule.
4
Factor out the common term e2xe^{2x}
dydx=e2x(2tanx+sec2x)\frac{dy}{dx} = e^{2x}(2\tan x + \sec^2 x).
Simplifying to match standard exam response format.

Key Concept

Differentiation of Exponential and Trigonometric Functions using the Product Rule
Estimated Time:1m 30s
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