A question on my test: Solve each equation over the interval [0°, 360°). If a decimal approximation is necessary, round to four decimal places. cos 2x -cos x-2 = 0

180degrees

Step-by-step explanation:

Given the expression cos^2x - cos x - 2 = 0

Let P = cos x

P^2 - P - 2 = 0

Factorize

P^2 - 2P + P - 2 =0

P(P-2)+1(P-2) = 0

P-2 = 0 and P + 1 = 0

P = 2 and P = -1

Since P = cos x

cos x = -1

x = arccos(-1)

x = 180degrees

Hence the require angle is 180degrees

b) 36

step-by-step explanation:

18 times 2 is 36

x= -3 and

step-by-step explanation:

to find the roots of a cubic, use division or factoring to find the factors then set equal to 0. as this is a difference of cubes, it factors into

where a is the cube root of .

here   this is 27 and the cube root of 27 is 3. so we write using the form:

.

set each factor to 0 and solve for x.

x-3=0

x=3

the quadratic expression does not factor and must be solved using the quadratic formula.

where a = 1, b=3, and c=9

this cubic has two complex roots.