(a)

Observe the graph.

Find .

The solid dot indicates the value of the function.

The value of the function at  is .

.

Find .

The solid dot indicates the value of the function.

The value of the function at  is .

.

Find .

Substitute  and  in the above function.

.

Find .

Substitute  and  in the above function.

.

Compare the values of  and .

Hence, .

(b)

 is the slope of the tangent at .

Draw a tangent line to the curve at .

Consider two points on the tangent line as  and .

Slope of a tangent line with points  and  : .

Slope of the tangent line : .

.

Find .

                     (From )

Compare the values of  and .

Hence, .

(a) .

(b)  .