int_1^7sqrt(x)lnxdx = 2/3int_1^7lnx d(x^(3/2))
int_1^7sqrt(x)lnxdx = 2/3(x^(3/2)lnx )|_(x=1)^(x=7) - 2/3int_1^7x^(3/2)d(lnx)
int_1^7sqrt(x)lnxdx = 2/3(x^(3/2)lnx )|_(x=1)^(x=7) - 2/3int_1^7x^(3/2)dx/x
int_1^7sqrt(x)lnxdx = 2/3(x^(3/2)lnx )|_(x=1)^(x=7) - 2/3int_1^7x^(1/2)dx
int_1^7sqrt(x)lnxdx = 2/3x^(3/2)(lnx - 2/3)|_(x=1)^(x=7)
int_1^7sqrt(x)lnxdx = 2/3sqrt(343)(ln7 - 2/3)+4/9