Răspuns :
(2x+3)²=(2x)²+2×2x×3+3²
=4x²+12x+9
(2x-3)(2x+3)=(2x)²-3² =4x²-9
(x-1)²=x²-2x+1
4x²+12x+9-4x²-9+2×x²-2x+1 ..(+4x² si -4x² ;+9 si -9 se reduc)
12x+2x²-2x+1
=4x²+12x+9
(2x-3)(2x+3)=(2x)²-3² =4x²-9
(x-1)²=x²-2x+1
4x²+12x+9-4x²-9+2×x²-2x+1 ..(+4x² si -4x² ;+9 si -9 se reduc)
12x+2x²-2x+1