#help
35 messages · Page 1 of 1 (latest)
is this solving?
or js simplifuomg
1 - sin^2 x = 8 sin^2 x - 6 sin x
9 sin^2x - 6 sin x - 1 = 0
let u = sin x
9u^2 - 6u - 1 = 0
lemme try complete the square
acc
3 sin x - 1 squared is 9u^2 - 6u + 1
compared to the other one
you have to minus two and then add on the other side
9u^2 - 6u - 1 = 0
add 2 on both sides
9u^2 - 6u + 1 = 2
(3u - 1)^2 = 2
(3 sin x - 1)^2 = 2
Why
9u^2 - 6u - 1 = 0
(3u - 1)^2 - 1 - 1 = 0
9u^2-6u - 1 = 0
9[u^2 - 2/3 u] - 1 = 0
9[(u - 1/3)^2 - 1/9] - 1 = 0
9(u - 1/3)^2 - 1 -1 = 0
9(u - 1/3)^2 = 2
3(u - 1/3) x 3(u - 1/3) = 2
(3u - 1)(3u - 1) = 2
(3u - 1)^2 = 2
(3 sin x - 1)^2 = 2
bravo
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