1.

If P(x) be a polynomial with real coefficients such that P(sin2 x) = P(cos2 x), for all x ∈ [0, π/2]. Consider the following statements :I.  P(x) is an even function.II.  P(x) can be expressed as a polynomial in (2x– 1)2 I.  P(x) is a polynomial of even degreeThen.(A)   all are false(B)   only I and II are true(C)  only II and III are true (D)  all are true 

Answer»

Correct option (C) only II and III are true 

Explanation:

P(sin2 x) = P(cos2 x)

P(sin2 x) = P(1 – sin2 x)

P(x) = P(1 – x) ∀ x  [0, 1]

Differentiable both sides w.r.t. x

P'(x) = – P'(1 – x)

So P '(x) is symmetric about point x = 1/2

So P '(x) has highest degree odd 

⇒ P(x) has highest degree even 



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