Question

b) 2 + 4 + 6 + ... + 100;

Answer 1

Răspuns:

2*1+2*2+2*3+...+2*50

2*(1+2+3+...+50) din care:

1+2+3+...+50=(50*51÷2)*2

=(2550÷2)*2

=1275*2

=2550