Răspunsuri

2014-05-25T20:46:17+03:00
A=(x+2)²-2(x+2)(x-2)+(x-2)²
a=x²+4x+4-(2x+4)(x-2)+(x²-4x+4)
a=x²+4x+4-2x²-4x+4x-8+x²-4x+4
a=0 ∈ N