Răspuns:
Explicație pas cu pas:
a)
1 + 2 + 3 + ... + 99 = 99*100/2 = 99*50
1/100 + 2/100 + 3/100 + 99/100 = (1 + 2 + 3 + ... + 99)/100 = 99*50/100 = 99/2
b)
4 + 8 + 12 + ... + 104 = 4*(1 + 2 + 3 + ... + 26) = 4*26*27/2 = 2*26*27
4/27 + 8/27 + 12/27 + ... + 104/27 = 2*26*27/27 = 2*26 = 52
c)
2 + 2/3 + 1/6 - 5/6 = 2 + 2/3 - 4/6 = 2 + 2/3 - 2/3 = 2
d)
3 1/4 - 3/4 = 13/4 - 3/4 = 10/4 = 5/2
e)
5 9/28 - 1 5/28 - 11/14 - 9/4
= 5 + 9/28 - 1 - 5/28 - 11/14 - 9/4
= 4 + 4/28 - 11/14 - 9/4
= 4 + 4/28 - 22/28 - 63/28
= 4 - 81/28
= 112/28 - 81/28
= 31/28