Question

Difficulty: MediumDifferentiation of Trigonometric, Exponential, and Logarithmic Functions

If y=e3xsin(2x)y = e^{3x} \sin(2x), what is dydx\frac{dy}{dx}?

  1. e3x(3sin2x+2cos2x)e^{3x}(3\sin 2x + 2\cos 2x)Answer
  2. B
    e3x(sin2x+cos2x)e^{3x}(\sin 2x + \cos 2x)
  3. C
    e3x(3sin2x2cos2x)e^{3x}(3\sin 2x - 2\cos 2x)
  4. D
    e3x(2sin2x+3cos2x)e^{3x}(2\sin 2x + 3\cos 2x)

Answer

e3x(3sin2x+2cos2x)e^{3x}(3\sin 2x + 2\cos 2x)
Using the product rule dydx=udvdx+vdudx\frac{dy}{dx} = u\frac{dv}{dx} + v\frac{du}{dx} on y=e3xsin(2x)y = e^{3x}\sin(2x) gives e3x2cos(2x)+sin(2x)3e3xe^{3x} \cdot 2\cos(2x) + \sin(2x) \cdot 3e^{3x}. Factoring out e3xe^{3x} results in e3x(3sin2x+2cos2x)e^{3x}(3\sin 2x + 2\cos 2x).

Step-by-Step Solution

1
Identify the function components for the product rule
Let u=e3xu = e^{3x} and v=sin(2x)v = \sin(2x).
The function yy is a product of two differentiable functions u(x)u(x) and v(x)v(x).
2
Differentiate each component using the chain rule
dudx=3e3x\frac{du}{dx} = 3e^{3x} and dvdx=2cos(2x)\frac{dv}{dx} = 2\cos(2x).
Applying the chain rule gives ddx(e3x)=3e3x\frac{d}{dx}(e^{3x}) = 3e^{3x} and ddx(sin2x)=2cos2x\frac{d}{dx}(\sin 2x) = 2\cos 2x.
3
Apply the product rule formula dydx=udvdx+vdudx\frac{dy}{dx} = u \frac{dv}{dx} + v \frac{du}{dx}
dydx=e3x(2cos2x)+sin(2x)(3e3x)=e3x(3sin2x+2cos2x)\frac{dy}{dx} = e^{3x}(2\cos 2x) + \sin(2x)(3e^{3x}) = e^{3x}(3\sin 2x + 2\cos 2x).
Combining the products and factoring out the common exponential factor e3xe^{3x} yields the final derivative.

Key Concept

Differentiation of Transcendental Functions using Product Rule and Chain Rule
Estimated Time:1m 30s
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