$\"\"$

(a)

Motion of particle is $\"\"$ .

Find the velocity of particle by applying derivative.

$\"\"$

Therefore the velocity of particle is $\"\"$ .

Equate it to zero.

$\"\"$

So the critical numbers are $\"\"$ and $\"\"$ .

$\"\"$

(b)

Consider the test intervals to find the interval of increasing and decreasing.

\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \

The sign of the velocity function is positive on the intervals $\"\"$ and $\"\"$ .

(c)

The sign of the velocity function is negative on the intervals $\"\"$ .

$\"\"$

(d)

At $\"\"$ and $\"\"$ , the velocity function changes its sign.

$\"\"$

(a) The velocity of particle is $\"\"$ .

(b) The sign of the velocity function is positive on the intervals $\"\"$ and $\"\"$ .

(d) Velocity function changes its direction at $\"\"$ and $\"\"$ .