Question

Afla valarea lui x
2+ 4 +6+........+ 98+X=1+2+3+4+5+.........+99
Litera corespunzatoare raspunsului corect este : a) 2 450 b) 2 500 c) 500 d) 50.

Answer 1

2+ 4 +6+........+ 98+x=1+2+3+4+5+.........+99
2(1+ 3 +4+........+ 49)+x=99×100:2
2×49×50:2+x=4950
2450+x=4950
x=4950-2450
x=2500
raspuns corect b. 2500