Write a formal proof to show that the conclusion is valid.

Determine whether the following statements are true and give an explanation or counterexample. bold a. when using the shell method, the axis of the cylindrical shells is parallel to the axis of revolution. bold b. if a region is revolved about the y-axis, then the shell method must be used. bold c. if a region is revolved about the x-axis, then in principle it is possible to use the disk/washer method and integrate with respect to x or the shell method and integrate with respect to y.

What is the number 321,000,000 in scientific notation? also what is the number? ?

The perimeter of a rectangle is 42 inches. if the width of the rectangle is 6 inches, what is the length