Question

13 Calculați:repedee​

Answer 1

Răspuns:

Explicație pas cu pas:

a)

1 + 2 + 3 + ... + 50 = 50*51/2 = 25*51 = 1275

b)

3 + 6 + 9 + ... + 90 = 3*(1 + 2 + 3 + ...+ 30) = 3*30*31/2 = 3*15*31 = 1395

Answer 2

Răspuns:

a)|-1|+|-2|+|-3|+.....+|-50|=1+|-2|+|-3|+.…+|-50|=1+2+|-3|+....+|-50|=1+2+3+...+|-50|=1+2+3+..…. +50=56

b)|-3|+|-6|+|-9|+...+|-90|=3+|-6|+|-9|+....+|-90|=3+6+|-9|+.....+|-90|=3+6+9+....+|-90|=3+6+9+....+90=108