phương trình căn x- 2020 + y - 2021 + z- 2022 = 1/2( x +y + z ) -3030 có nghiệm là
2 câu trả lời
Đáp án + Giải thích các bước giải:
`\sqrt{x-2020}+\sqrt{y-2021}+\sqrt{z-2022}=1/2 (x+y+z)-3030`
`⇔2\sqrt{x-2020}+2\sqrt{y-2021}+2\sqrt{z-2022}= x+y+z-6060`
`⇔(x-2020-2\sqrt{x-2020}+1)+(y-2021-2\sqrt{y-2021}+1)+(z-2022-2\sqrt{x-2022}+1)=0`
`⇔(\sqrt{x-2020}-1)^2+(\sqrt{y-2021}-1)^2+(\sqrt{z-2022}-1)^2=0`
`⇔{(\sqrt{x-2020}-1=0),(\sqrt{y-2021}-1=0),(\sqrt{z-2022}-1=0):}`
`⇔{(\sqrt{x-2020}=1),(\sqrt{y-2021}=1),(\sqrt{z-2022}=1):}`
`⇔{(x-2020=1),(y-2021=1),(z-2022=1):}`
`⇔{(x=2021),(y=2022),(z=2023):}`
Vậy pt có nghiệm `{(x=2021),(y=2022),(z=2023):}`
`\sqrt{x - 2020 } + \sqrt{y - 2021} + \sqrt{z - 2022} = 1/2 ( x + y + z ) - 3030`
`⇔ 2\sqrt{x - 2020} + 2\sqrt{y - 2021} + 2\sqrt{z - 2022} = x + y + z - 6060`
`⇔ ( x - 2020 - 2\sqrt{x - 2020} + 1 ) + ( y - 2021 - 2\sqrt{y - 2021} + 1 ) + ( z - 2022 - 2 \sqrt{x - 2022} + 1 = 0`
`⇔ ( \sqrt{x - 2020} - 1^2 ) + ( \sqrt{y - 2021} -1 ) ^2 + ( \sqrt{z - 2022} - 1)^2 = 0`
`⇔ {(\sqrt{x - 2020} - 1 = 0),(\sqrt{y - 2021} - 1 = 0),(\sqrt{z - 2022} - 1 = 0):}`
`⇔ {(\sqrt{x - 2020} = 1 ),(\sqrt{y - 2021} =1),(\sqrt{z - 2022} = 1):}`
`⇔ {(x - 2020 = 1),(y - 2021 = 1),(z - 2022 = 1):}`
`⇔ {(x = 2021),(y = 2022),(z = 2023):}`
Vậy phương trình có nghiệm `{(x = 2021),(y = 2022),(z = 2023):}`