Vì `( x - 2 )^2020 ≥ 0 AA x , ( y - 5 )^4 ≥ 0 AA x` mà `( x - 2 )^2020 + ( y - 5 )^4 ≤ 0`
`⇒ ( x - 2 )^2020 + ( y - 5 )^4 = 0`
`⇔` $\left \{ {{( x - 2 )^{2020} = 0} \atop {( y - 5 )^4 = 0}} \right.$
`⇔` $\left \{ {{x - 2 = 0} \atop {y - 5 = 0}} \right.$
`⇔` $\left \{ {{x = 2} \atop {y = 5}} \right.$
Vậy `, x = 2 , y = 5 .`