Prove the identity.cos 2x = 2 cos4 x + 2 sin2x cos2x - 1
What will be an ideal response?
2 cos4 x + 2 sin2x cos2x - 1
= 2 cos2x(cos2x + sin2x ) - 1
= 2 cos2x ? 1 - 1 Using the Pythagorean identity
= 2 cos2x - 1
= cos 2x Using the double-angle identity
Mathematics
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The double-line graph shows temperature highs and lows for a week. 
What was the low temperature reading on Thursday?
Fill in the blank(s) with the appropriate word(s).
Mathematics
Factor the expression completely.375k3m - 81m4
A. (15km - 9m2)(25k2 + 9m2) B. 3m(5k - 3m)(25k2 + 15km + 9m2) C. 3m(5k + 3m2)(25k2 - 15km + 9km2) D. 3m(125k - 3m)(k2 + 15km + 9m2)
Mathematics
Solve the equation.-10.9x + 1.8 = -63.3 - 1.6x
A. {7} B. {6.1} C. {6} D. {-74}
Mathematics
Find the distance between P and Q and the coordinates of the midpoint of the segment joining P and Q.
A. 
; 
B. 
; 
C. 
; 
D. 
; 
Mathematics