Réponse :
Explications étape par étape
Bonjour
2) a) Developper :
(1 - x)(-2 - y)
= 1 * (-2) - 1 * y - x * (-2) - x * (-y)
= -2 - y + 2x + xy
b) développer :
(-2x + 3)(-1 - y)
= -2x * (-1) - 2x * (-y) - 3 * 1 - 3 * y
= 2x + 2xy - 3 - 3y
3) a) -(-x + y) - (2x + 5y)
= x - y - 2x - 5y
= -x - 6y
b) -(2x - 3y) + (-x - y)
= -2x + 3y - x - y
= -3x + 2y
4) -1/6 - 2/3
= -1/6 - (2 x 2)/(2 x 3)
= -1/6 - 4/6
= -5/6
-1/2 - 7/4
= -(1 x 2)/(2 x 2) - 7/4
= -2/4 - 7/4
= -9/4
-1/25 - 1/20
= -(1 x 4)/(25 x 4) - (1 x 5)/(5 x 20)
= -4/100 - 5/100
= -9/100
-1/3 + 1/12
= (-1 x 4)/(3 x 4) + 1/12
= -4/12 + 1/12
= (-3/12)
= (-3)/(3 x 4)
= -1/4
-1/27 + 1/9
= -1/27 + (1 x 3)/(3 x 9)
= -1/27 + 3/27
= 2/27
5) développer :
A = (-5)(2x + 3)
A = (-5) * 2x - 5 * 3
A = -10x - 15
