3. The arithmetic mean of 9, 11, 13, x and 7 is 10. What is the value of x?

What is the product of the radical expression. (7-2square root) (8+2 square root)

Translate the word phrase into a math expression. 15 fewer than the product of 4 and a number. (pls immediately)

Which sum or difference identity would you use to verify that cos (180° - ∅) = -cos ∅? a. sin (α -β) = sin α cos β – cos α sin β b. cos (α -β) = cos α cos β – sin α sin β c. cos (α -β) = cos α cos β + sin α sin β d. sin (α + β) = sin α cos β + cos α sin β