How do you verify $2 + cos^2 x - 3 cos ^4 x = sin^2 x(2 +3 cos^2 x)$ ?

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Answer 1 · 2018-03-08T20:00:59

Use $sin^2x = 1- cos^2x$ .

RHS:

$(1 - cos^2x)(2 + 3cos^2x)$

$2 - 2cos^2x + 3cos^2x - 3cos^4x$

$2 + cos^2x- 3cos^4x$

LHS:

$2 + cos^2x - 3cos^4x$

LHS = RHS

Hopefully this helps!

How do you verify 2 + cos^2 x - 3 cos ^4 x = sin^2 x(2 +3 cos^2 x)2 + cos^2 x - 3 cos ^4 x = sin^2 x(2 +3 cos^2 x)?