Question

daca x+y = 2 , si $x^{2} +5x=4$  ,atunci cat este y

Answer 1

x+y=2 => x=2-y
=> (2-y) ² + 5(2-y)= 4
4-4y+ y²+10-5y=4
y²-9y+10=0
y(y-9)= -10
y= -10
y-9=1 => y= 10
y=1
y-9= -10 => y= -1
y=-2
y-9=5 => y= 14
y=5
y-9= -2 => y= 7
etc (iei toate posibilitatile  1· (-10) , (-1)·10 , (-2)·5, 2·(-5) .