Question

Determina numerele x și y, știind că xy +3x+3y+9=21.

Answer 1

xy +3x+3y+9=21
x(y+3)+3(y+3)=21
(x+3)(y+3)=21    divizorii lui 21 (-21,-7,-3,-1,1,3,7,21)

x+3=-21   x=-24
y+3=1      y=-2

x+3=-7   x=-10
y+3=-3    y=-6

x+3=-3   x=-6
y+3=-4   y=-7

x+3=-1   x=-4
y+3=-21  y=-24

x+3=1   x=-2
y+3=21 y=18

x+3=3   x=0
y+3=7  y=4

x+3=7   x=4
y+3=3   y=0

x+3=21   x=18
y+3=1     y=-2