Bonjour,
Ex. 1 :
1) non car 6x = 4x + 2x et pas 4 + 2x
2) non car -x + x = 0
3) oui car (3x)² = 3²x² = 9x²
4) non car (3+x)² = 9+6x+x²
5) non car 2x × 4x = 8x²
6) non car 2x + 4x = 6x
Ex. 2 :
3(x+2) = 3x+6
-2(3x-5) = -6x+10
x(x-2)-(2x-2) = x²-2x-2x+2 = x²-4x+2
(x+2)(x+3) = x²+3x+2x+6 = x²+5x+6
(3-x)(1-x) = 3-3x-x+x² = x²-4x+3
(2x-3)(3x+4) = 6x²+8x-9x-12 = 6x²-x-12
2(x-1)(x+1) = 2(x²-1²) = 2x²-2
(x+3)² = x²+6x+9
(2x-1)² = 4x²-4x+1
4+(x-2)² = 4+x²-4x+4 = x²-4x+8
5(1-3x)-(2x+3)(x-1) = 5-15x-(2x²-2x+3x-3) = 5-15x-2x²+2x-3x+3 = -2x²-16x+8
