Find the intervals in which the following functions are strictly increasing or decreasing:

Question

Find the intervals in which the following functions are strictly increasing or decreasing: 10 – 6x – 2x 2

Philoid · Accepted Answer

It is given that function f(x) = 10 – 6x – 2x²

f’(x) = -6 – 4x

If f’(x) = 0, then we get,

⇒ x =

So, the point x = divides the real line into two disjoint intervals,

So, in interval

f’(x) = -6 – 4x < 0

Therefore, the given function (f) is strictly decreasing in interval.

And in interval

f’(x) = -6 – 4x > 0

Therefore, the given function (f) is strictly increasing in interval.

Thus, f is strictly decreasing for x> .