Maths(INTEGRAL by substitution)

put u = 3√x
du = 1/3 (3√x^2 ) dx
when x = 1, u = 1; when x = 8, u = 2
(integral 8 1) e^3√x / 3√x^2 dx
(integral 2 1) 3 e^u du = 3(e^2 - e)

第2題有冇打錯題目?應做唔到

第二題應該做到, 因為我幾日前也曾問過.
個答案我明左一半, 不過你可以參考下.

http://hk.knowledge.yahoo.com/question/?qid=7007100403007