E(x) =4x²+12x+9
-x² +4
-3x²+6x -3=
=18x+10
E(1) +E(2)+....+E(25)=18(1+2+...+25) +10*25=18*25*26/2+250=5850+250=6100
problema 5
n=4a+3
n=6b+5
n=9c+8
n+1=4a+3+1=4a+4=4(a+1)=4d
n+1=6b+5+1=5b+5=6(b+1)=6e
n+1=9c+8+1=9c+9=9(c+1)=9f
n+1 divizibil cu 4;5;9⇒n+1 divizibil cu [4,6,9]=4*9=36
n+1=36k
n=36k-1
100<n<250
convin 3*36-1=107
4*36-1=143
5*36-1=179
6*36-1=215
