Question

Ex 34 va roooooggggg

Answer 1

1+2+...+n=n(n+1)/2
a} 1+2+3+...+45=45x46/2=45x23=1035
b) 2+4+6+....+200=2(1+2+3+....+100)/2=100x101/2=50x101=5050
c) 3+6+9+...+330=3(1+2+3+....+110)=3x110x111/2=333x55=18315
d) 45+46+47+....+95=(1+2+3+.....+95)-(1+2+3+....+44)=
     95x96/2-44x45/2=95x48-22x45=4560-990=3570
e) 102+103+104+...+199=(1+2+3+....+199)-(1+2+3+....+101)=
     199x200/2-101x102/2=199x100-101x51=19900-5151=14749