Explications étape par étape:
1)
6× 2 = 12
12-1= 11
11× 11 = 121
121-64 = 57
2)
-2×2 = -4
-4-1= -5
-5 × (-5) = 25
25 -64 = -39
3)
x × 2 = 2x
2x -1= 2x -1
(2x-1)(2x-1) = 4x² -2x -2x +1 = 4x²-4x +1
4x²-4x +1-64 = 4x²-4x -63
4)
(2x-9)(2x+7) = 4x² +14x -18x -63 = 4x² -4x -63
