∫xlnxdx步骤详解

Answer 1

∫xlnxdx
=(1/2)∫lnxdx^2
=(1/2)x^2.lnx - (1/2)∫x dx
=(1/2)x^2.lnx - (1/4)x^2 + C

追问

第二张，我圈出来的，，不懂，能给我解释解释吗

追答

dx^2 = 2x dx
xdx =(1/2) dx^2

dlnx = (1/x) dx
∫ xlnx dx
=(1/2)∫ lnx dx^2
=(1/2)x^2.lnx - (1/2)∫ x^2 dlnx
=(1/2)x^2.lnx - (1/2)∫ x dx
=(1/2)x^2.lnx - (1/4)x^2 + C