F5 math m1 indefinite integral

If n is a positive integer, then
d((x^n)lnx)/dx =nx^(n-1) lnx+x^(n-1)
Question:
a) deduce that x^(n)lnx+C1 = (integral sign)nx^(n-1)lnx dx +x^(n)/n, where C1 is an arbitrary constant
b) using the result in(a), show that (integral sign)x^(6)lnx dx=(x^(7)lnx)/7 - x^(7)/49 + C, where C is an arbitrary constant

Please help, Thank you!!