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Solve on the interval [0,2pi). (cosx + 1) (2cos^2 x-3 cosx -2) = 0

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User Trastle
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1 Answer

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Answer: To solve the equation (cosx + 1)(2cos^2 x - 3cosx - 2) = 0, we'll first find the values of x that make each factor equal to zero and then find the corresponding solutions for x in the given interval [0, 2π).

Step 1: Set each factor equal to zero and solve for x:

cosx + 1 = 0

Subtract 1 from both sides:

cosx = -1

2cos^2 x - 3cosx - 2 = 0

This is a quadratic equation. Let's factor it:

2cos^2 x - 3cosx - 2 = (2cosx + 1)(cosx - 2)

Now, set each factor equal to zero:

2cosx + 1 = 0

cosx = -1/2

cosx - 2 = 0

cosx = 2 (Note: Cosine values are always between -1 and 1, so there is no solution for this equation.)

Step 2: Find the solutions for x in the interval [0, 2π):

For cosx = -1, the solutions in the given interval are π (180 degrees) and 3π (540 degrees).

For cosx = -1/2, the solutions in the given interval are π/3 (60 degrees) and 5π/3 (300 degrees).

So, the solutions for x in the interval [0, 2π) are:

x = π, π/3, and 5π/3.

answered
User Halliewuud
by
7.8k points

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