Question

Find all solution of the following equation in the interval [0, 2pi) No decimals.

7cos x + 9 = -2cos x

Answer 1

Explanation:

Step 1: Add 2cos(x) to both sides

`7cos(x) + 2cos(x) + 9 = -cos(x) + cos(x)`

`9cos(x) + 9 = 0`

Step 2: Subtract 9 from both sides

`9cos(x) + 9 - 9 = 0 - 9`

`9cos(x) = -9`

Step 3: Divide both sides by 9

`9cos(x) / 9 = -9 / 9`

`cos(x) = -1`

Step 4: Find x

`cos^-^1(-1) = x`

`\pi = x`

Answer:
`x = \pi`