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Question
The function f(x) = x9 + 3x7 + 64 is increasing on
Options
R
(−∞, 0)
(0, ∞)
R0
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Solution
R
\[f\left( x \right) = x^9 + 3 x^7 + 64\]
\[f'\left( x \right) = 9 x^8 + 21 x^6 > 0, \forall x \in R\]
\[\text { So, f(x) is increasing on R } .\]
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