Question

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Answer 1

Quick question, what level math are you in?

Answer 2

I'm guessing this is calc?

Answer 3

yeah

Answer 4

\[f \prime \left( x \right)=135x^2-15x^4=15x^2\left( 9-x^2 \right)\]
f(x)decreases if f'(x)<0
\[if ~15x^2\left( 9-x^2 \right) <0,x^2\ge0,\]
Hence ~f'(x)<0, if
\[9-x^2<0,9<x^2~or~x^2>9,\left| x \right|>3,\]
including end points f(x) decreases if
\[\left| x \right|\ge3,x \le-3,x \ge3\]
\[x \in (- \infty,-3]\cup[3,\infty)\]

Answer 5

thank youu!!!!!!

Answer 6

yw