math , physics, chemistry
posted by vikas
sec^4x=11tan^2x+5 than what is the value of tanx

Steve
sec^4x=11tan^2x+5
(1+tan^2x)^2 = 11tan^2x+5
tan^4x + 2tan^2x + 1  11tan^2x  5 = 0
tan^4x  9tan^2x  4 = 0
That's just a quadratic in tan^2x, so solve it, then just take the square root.
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