Réponse:
(2x×2x+3×3)-(x×x-4×4)
(4x2+9)-(x2-16)
4x2+x2-7
(2x²+3²+2×2x×3)-(x²+4²-2x×4)
2x²+9+12x-x²-16+8X
X²+20X-25