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Question
The function f(x) = x3 + 3x is increasing in interval ______.
Options
(– ∞, 0)
(0, ∞)
R
(0, 1)
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Solution
The function f(x) = x3 + 3x is increasing in interval R.
Explanation:
f(x) = x3 + 3x
`\implies` f'(x) = 3x2 + 3
= 3(x2 + 1) > 0
So function increases for all real values of x ∈ R.
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