Questions:
X x X= X au carré
X + X= 2X
Exo 1
-3X(5X+8)
= -3X x 5X + (-3)X x 8
= -15X au carré + -24X
(4-5X)(6X+10)
=4 x 6X + 4 x 10 -5X x 6X -5X x 10
=24X + 40 -30X au carré -50
=-30X au carré + 24X -10
Exo 2
5X au carré -9X
= X(5X-9)
-36X + 18
= -18x2 + 18
= 18(-2+1)
(2X+3)(X-4)+(X-4)(5X-7)
= (X-4)(2X+3+5X-7)
=(X-4)(7X-4)