Bonjour,
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Je rappelle les identités remarquables :
(a+b)²=a²+2ab+b²
(a-b)²=a²-2ab+b²
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(a-4)²=a²-2×a×4+4²
(a-4)²=a²-8a+16
(3m-1)²=(3m)²-2×3m×1+1²
(3m-1)²=9m²-6m+1
(2t+1)²=(2t)²+2×2t×1+1²
(2t+1)²=4t²+4t+1
(2t-1)²=(2t)²-2×2t×1+1²
(2t-1)²=4t²-4t+1
99²=(100-1)²
99²= 100²-2×100×1+1²
99²= 10 000 - 200 +1
99²=9 800 +1
99²=9 801