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`(x+1)^{x+1} = (x+1)^{x+3}`
`-> (x+1)^{x+1}-(x+1)^{x+3}=0`
`-> (x+1)^{x+1} - (x+1)^{x+1} . (x+1)^2 =0`
`-> (x+1)^{x+1} [1 - (x+1)^2]=0`
TH1 :
`(x+1)^{x+1}=0`
`-> x+1=0`
`->x=-1`
TH2 :
`1-(x+1)^2=0`
`->(x+1)^2=1`
`-> (x+1)^2=1^2` hoặc `(x+1)^2=(-1)^2`
`->x+1=1` hoặc `x+1=-1`
`->x=0` hoặc `x=-2`
Vậy `x=0,x=-2,x=-1`