Question

Aflați numărul x care verifică egalitatea 1 plus 3 plus 5 plus puncte puncte puncte plus 99 plus x egal 2 plus 4 plus 6 plus puncte puncte puncte plus 100​

Answer 1

Răspuns:

1+3+5+...+99+x=2+4+6+..+100

1+2+3+4+5+....+98+99+x-(2+4+6+...+98)

99×100÷2+x-98×99:2+

990:2+x-9702:2

495+x-4851 =2×1+2×2+2×3+2×4+...+2×50

= 2×(1+2+3+...+50)

=2×50×51:2

=2550

495+x-4851=2550

495+x=2550+4851

495+x=7401

x=7401-495=>x=6906