Q. Evaluate the integral and express your answer in simplest form.∫16−4x2−7dxAnswer:
Choose Trig Substitution: We are given the integral: ∫16−4x2−7dxTo solve this integral, we can use a trigonometric substitution. Let's choose x=2sin(θ), because the expression under the square root resembles the Pythagorean identity 1−sin2(θ)=cos2(θ).
Find dx: Differentiate x=2sin(θ) with respect to θ to find dx:dθdx=2cos(θ)dx=2cos(θ)dθ
Substitute x and dx: Substitute x=2sin(θ) and dx=2cos(θ)dθ into the integral:∫16−4(2sin(θ))2−7⋅2cos(θ)dθSimplify the expression under the square root:∫16−16sin2(θ)−7⋅2cos(θ)dθ
Simplify Expression: Recognize that 16sin2(θ) is a multiple of the Pythagorean identity, so we can simplify further:∫16(1−sin2(θ))−7⋅2cos(θ)dθSimplify the square root using the identity 1−sin2(θ)=cos2(θ):∫4cos(θ)−7⋅2cos(θ)dθ
Cancel Cos Terms: Cancel out the cos(θ) terms:∫4cos(θ)−7⋅2cos(θ)dθ=∫4−7⋅2dθSimplify the constant factors:∫2−7dθ
Integrate with Respect: Integrate with respect to theta: (−27)∫dθ=(−27)θ+C
Express Θ in x: Now we need to express θ in terms of x. Since x=2sin(θ), we can write sin(θ)=2x. To find θ, we take the inverse sine (arcsin) of both sides:θ=arcsin(2x)Substitute θ back into the integral result:\(\left(-\frac{\(7\)}{\(2\)}\right) * \theta + C = \left(-\frac{\(7\)}{\(2\)}\right) * \arcsin\left(\frac{x}{\(2\)}\right) + C
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