Prove that f (x) = ax + b, where a and b are constants and a > 0 is an strictly increasing function for all real values of x. without using the derivative.
Prove that the function f(x) = x3 – 3x2 + 3x – 100 is increasing on R.
Here (x) = x3 – 6x2 + 12x – 18 ∴ Df = R
f ' (x) = 3 x2 – 12x + 12 = 3 (x2 – 4 x + 4) = 3 (x – 2)2 ≥ 0 ∀ x ∊ R
∴ (x) is increasing on R.
Prove that the function f (x) = sinx is
(i) strictly increasing in
(ii) strictly decreasing in
(iii) neither increasing nor decreasing in .
Prove that the function f (x) = cos x is
(i) strictly increasing in
(ii) strictly decreasing in
(iii) neither increasing nor decreasing in