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Step 3 of 4 Use the two critical points to divide the real line into three intervals.

`(-\infty ,-6),(-6,-5),(-5,\infty )`

To determine where

`f(x)`

is increasing or decreasing, pick an

`x`

-value in each interval, and identify the sign of

`f^(')(x)`

. Let's pick

`x_(1)=-7`

in the first interval,

`x_(2)=-5`

in the second interval, and

`x_(3)=0`

in the third interval. Fill in the table below with the appropriate sign. \table[[Interval,

`x`

-value,Sign of

`f^(')(x)`