D Question 21 Express the sum or difference as a product. sin 10x - sin 4x 2 cos 4x Cos 7x O 2 sin 7x cos 3x 2 sin 3x cos 7x O 2 sin 3x Question 22D Question 22 Write the expression as the sine, cosine, or tangent of a double angle. Then find the exact value of the expression 2 sin 22.5 cos 22.50 O V2 O . V2 N O - OQuestion 23 Find the exact value of the expression. cos - sin - - cos - T sin 12 O O 01 OD Question 24 Complete the identity. 2 tan x - (1 + tan x) 2 = ? 0 1 O - sec2 x 1 - sin x 0 0D Question 25 Write the partial fraction decomposition of the rational expression. 17x + 54 x2+6x + 8 O 10 + X x - 2 O 7 -10 + x + 4 x + 2 O S 9 + x+4 x +2 O 7 10 * +4 x+2D Question 26 Find and simplify the difference quotient h zo for the given function. f (x ) = x2+ 9x+4 O 2 x th + 4 O 2x th+9 01 O 2x2+ 2x + 2xh + h2+h+8 h