développer, puis réduire chaque expression. a) x(x - 4) + x au carré b) x(2x + 5) - x c) (x + 1)(x + 2) d) (x + 5)(x - 1) e) (2x + 1)(3x + 1) f) (x - 3)(x - 4)

a) x(x - 4) + x²
=x²-4x+x²
=2x²-4x

b) x(2x + 5) - x
=2x²+5x-x
=2x²+4x

c) (x + 1)(x + 2)
=x²+2x+x+2
=x²+3x+2

d) (x + 5)(x - 1)
=x²-x+5x-5
=x²+4x-5

e) (2x + 1)(3x + 1)
=6x²+2x+3x+1
=6x²+5x+1

f) (x - 3)(x - 4)
=x²-4x-3x+12
=x²-7x+12