Question

calculati uramtoarele sume a)2+4+6+8+.......+200=; b) 5+10+15+20......+250=
ajutatima va rogg dauu coronita​

Answer 1

a)2+4+6+8+.......+200=

2(1+2+3+4+5+..+100)=

2x 100x101/2=

100x101=

=10100

b) 5+10+15+20......+250=

5(1+2+3+...+50)=

5x 50x51/2=

5x25x51=

=6375

Succes!

Answer 2

Răspuns:

    a) 10100

    b) 6375

Explicație pas cu pas:

    a) 2 + 4 + 6 + 8 + ... + 200

    2(1 + 2 + 3 + 4 + ... + 100)

    2 · (100 + 1) · 100 ÷ 2

    2 · 101 · 50 = 10100

    b) 5 + 10 + 15 + 20 + ... + 250

    5(1 + 2 + 3 + 4 + ... + 50)

    5 · (50 + 1) · 50 ÷ 2

    5 · 51 · 25 = 6375