In your own words, explain why Devyn and Riley claim we should never pick {{MATH_40}} or {{MATH_41}} to be the entire integrand. {{CMD_42}} The goal of substitution is to make the integral easier to do. Your choices for {{MATH_43}} and {{MATH_44}} should make things easier, not harder! Unless the derivative of {{MATH_45}} is {{MATH_46}}, choosing {{MATH_47}} to be the entire integrand means that you don't have any part of the integrand left to be the derivative of {{MATH_48}}. Choosing {{MATH_49}} means that {{MATH_50}}, meaning that you haven't simplified the integral at all. {{CMD_51}} {{CMD_52}}