Question

31**. Calculaţi:
a) 1+2+3 + ... +8+9;
c) 1+2+3+...+99+100;
32**. Calculaţi:
a) 1+3+5+...+97 +99;
c) 2+4 +6+...+98+100;
e) 1+5+9+...+97+101;​

Answer 1

Explicație pas cu pas:

a. (9×10)÷2=90÷2=45

c.(100×101)÷2=10100÷2=5050

Answer 2

Răspuns:

a)1+2+3...+9=10x9÷2=45

c)1+2+3+....100= 101x100÷2=10100÷2=5050

a)1+3+...99=99x99=9801

c)2+4+6+....98=2(1+2+3+...49)

=2×(49x50÷2)=2×1225=2450