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ewkmath
 one year ago
what is X when 2sin^2(X)+9cos(X)+3=0
ewkmath
 one year ago
what is X when 2sin^2(X)+9cos(X)+3=0

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Shadowys
 one year ago
Best ResponseYou've already chosen the best response.4have you subbed \(\sin^2 x x = 1\cos^2 x\) into the eq to simplify it into a quadratic eq?

ewkmath
 one year ago
Best ResponseYou've already chosen the best response.0no i haven't but i'll try it out right now thanks :)

Shadowys
 one year ago
Best ResponseYou've already chosen the best response.4u r welcome. The solution should be trivial after the substitution. :)

ewkmath
 one year ago
Best ResponseYou've already chosen the best response.0I tried it but i still don't get it..

Shadowys
 one year ago
Best ResponseYou've already chosen the best response.4subbing, you should get, \(22\cos^2 x + 9 \cos x +3=0\) which equals, \(2\cos^2 x + 9 \cos x +5=0\) let u = cos x the equation becomes \(2u^2 + 9 u +5=0\) which is a quadratic equation of u. You can use the general formula to solve for u.

ewkmath
 one year ago
Best ResponseYou've already chosen the best response.0thanks o much.. i really appreciate it
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