The function f x = 4 x 3 - 3 x 2 6 - 2 sin x + 2 x - 1 cos x :

Question

The function f x = 4 x 3 - 3 x 2 6 - 2 sin x + 2 x - 1 cos x :, increases in 1 2 , ∞, decreases in - ∞ , 1 2, decreases in 1 2 , ∞, increases in - ∞ , 1 2

MARKS App · Accepted Answer

f x = 4 x 3 - 3 x 2 6 - 2 sin x + 2 x - 1 cos x f ' x = 2 x 2 - x - 2 cos x + 2 cos x - sin x 2 x - 1 . = 2 x - 1 x - sin x for x > 0 , x - sin x > 0 x 0 , x - sin x 0 for x ∈ - ∞ , 0 ∪ 1 2 , ∞ , f ' x ≥ 0 for x ∈ 0 , 1 2 , f ' x ≤ 0 ⇒ f x increases in 1 2 , ∞

Search any question & find its solution

Looking for more such questions to practice?