Question

Find the exact area of the surface obtained by rotating the curve about the x-axis.

y = 

1 + 5x

,    1 ≤ x ≤ 7

 

Answer 1

Step 1:

The curve is , .

Re write the curve equation is .

If the curve is rotating about axis, area of the resultant surface is .

Where 

Step 2:

Substitute and  in area formula.

Solution:

The area of the surface is  Sq-units.