Bonjour,
26 × 14 = 26 × (10 + 4) = 26 × 10 + 26 × 4 = 260 + 104 = 304
56 × 19 = 56 × (20 - 1) = 56 × 20 - 56 × 1 = 1 120 - 56 = 1 064
17 × 102 = 17 × (100 + 2 ) = 17 × 100 + 17 × 2 = 1 700 + 34 = 1 734
tu fais le dernier ? en sachant que 99 = 100 - 1
6x(2x-1)-(7x²-3x+1)+1 = 12x²-6x-7x²+3x-1+1 = 5x²-3x
-4x(x-7)-3x(-2x+5)-3 = -4x²+28x+6x²-15x-3 = 2x²+13x-3
