Question

Calculrază:a.1+2+3+...32. b.274+6+8+...+80. c.5+10+15+...+550. d.10+20+30+..330.

Answer 1

a. (1+32)×32/2=
33×32/2=
33×16=
528
b. 2(1+2+...+40)=
-facem suma din paranteza
(1+40)×40/2=
41×40/2=
41×20=
820
820×2=1640
c. 5(1+2+...+110)=
(1+110)×110/2=
111×110/2=
111×55=
6 105
6105×5=30525
d. 10(1+2+...+33)=
(1+33)×33/2=
34×33/2=
17×33=
561
561×10=5610
Sper ca te-am ajutat

Answer 2

a)1+2+3+...+32=

=32(32+1):2=32*33:3=1045:3=352

b)274+6+8+...+80=

=80(80+274):6=80*354:6=28360:6=4720

c)5+10+15+...+550=

=550(550+5):10=550*555:10=305250:10=30525

d)10+20+30+....+330=

=330(330+10):20=330*340:20=112200:20=5610