Question

Ajutor cu ex de la 6 la 10 dau 10 puncte şi coroana.

Answer 1

6.
a) l-ai facut
b)2x+12≥3x, x≤12, x∈{0;1;2;......12}
c)2x+12≥20, 2x≥8, x≥4, x∈N

7.3(17-6)-x≥3
x≤30, x∈{0;1;2;3;......30}
S=1+2+3+...........+30=31 x 30/2
S=465

8.
1+3+5+...........+99=(99+1) x 50/2 = 2500
2+4+6+...........100=(100+2) x 50/2=2550
2500 < x <2550, x∈N

9.
x(1+2+3+................2013)=1007^2 x 2013
x[(2013+1) x 2013/2]=1007^2 x 2013
x (1007 x 2013)=1007^2 x 2013
x=1007

10.
S=1+2+2^2+2^3+..............2^2012
2S=2+2^2+2^3+................2^2013
2S-S=2^2013 - 1
S=2^2013 -1
2^2013 - 1 - x = 2^2013 - 2

x=1