If y=( sin x+ cos x)+( sin 4 x+ cos 4 x)2, then -

Question

If y=( sin x+ cos x)+( sin 4 x+ cos 4 x)2, then - (A) y>0 ∀ x ∈ R (B) y ≥ 0 ∀ x ∈ R (C) y<2+√2 x ∈ R (D) y=2+√2 for some x ∈ R

Tardigrade Admin · Accepted Answer

Correct answer is (c) y<2+√2 x ∈ R

Q. If $y = (sin x + cos x) + (sin 4 x + cos 4 x)^{2}$ , then -