Răspuns:
Explicație pas cu pas:
3a)
E(x)=x²(x+3)-4(x+3)=(x+3)(x²-4)=(x+3)(x+2)(x-2)
3b)
E(x)=(x+2)²-(x-1)²-2(x+3)-5=[(x+2-x+1)(x+2+x-1)]-2x-11=
= 3(2x+1)-2x-11=6x+3-2x-11=4x-8
0<E(n)≤11
0<4n-8≤11
4n≤19 n≤4,75
8<4n n>2 ⇒n={3,4}
