Réponse:
a) (x+2)² = x²+2×x×2+4
=x²+4x+4
b) (x-8)² = x²-2×x×8+64
=x²-16x+64
c) (x-5)(x+5) = x²+5x-5x-25
=x²-25
d) (3x-4)² = 9x²-2×3x×4+16
=9x²-24x+16
e) (7a+6b)² = 49a²+2×7a×6b+36b²
= 49a²+84ab+36b²
f) (2y+9)(2y-9) = 4y²-18y+18y-81
=4y²-81
g) (6x-5)²+(7x-2)(x+3)
= 36x²-2×6x×5+25+7x²+21x-2x-6
=36x²-60x+25+7x²+21x-2x-6
=43x²-41x+19
h) 7(2x-1)-(8x+2)(8x-2)+(x-3)²
=14x-7-(64x²-4)+x²-6x+9
=8x+6-63x²
