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Section 5.1[ATTACH=full]1235[/ATTACH]Question 306 cos^2 x + 5 cos x - 6Let u = cos x6u^2 + 5u - 6Factor by grouping.6(-6) = -369(-4) = -369 + (-4) = 56u^2 + 9u - 4u - 66u^2 + 9u becomes 3u(2u + 3)-4u - 6 becomes -2(2u + 3)We now have (3u - 2)(2u + 3).Back-substitute for u.(3cos x - 2)(2cos x + 3)You say?
Section 5.1
[ATTACH=full]1235[/ATTACH]
Question 30
6 cos^2 x + 5 cos x - 6
Let u = cos x
6u^2 + 5u - 6
Factor by grouping.
6(-6) = -36
9(-4) = -36
9 + (-4) = 5
6u^2 + 9u - 4u - 6
6u^2 + 9u becomes 3u(2u + 3)
-4u - 6 becomes -2(2u + 3)
We now have (3u - 2)(2u + 3).
Back-substitute for u.
(3cos x - 2)(2cos x + 3)
You say?
