Question

化简:(a+b)+(2a+b/1*2)+(3a+b/2*3)+...+(10a+b/9*10)

Answer 1

(a+b)+(2a+b/1*2)+(3a+b/2*3)+...+(10a+b/9*10)

=a(1+2+……+10)+b(1+1-1/2+1/2-1/3+……+1/9-1/10)

=55a+(2-1/10)b

=55a+(19/10)