Tìm x (x-1)/2020 + (x-2)/2019=(x-3)/2018 + (x-4)/2017 14/11/2021 Bởi Ivy Tìm x (x-1)/2020 + (x-2)/2019=(x-3)/2018 + (x-4)/2017
Đáp án: ` (x-1)/2020 + (x-2)/2019 = (x-3)/2018 + (x-4)/2017` ` => ((x-1)/2020 – 1) + ((x-2)/2019-1) = ((x-3)/2018-1) + ((x-4)/2017-1)` ` => (x-2021)/2020 + (x-2021)/2019 = (x-2021)/2018 + (x-2021)/2017` ` => (x-2021) * (1/2020 + 1/2019 – 1/2018 – 1/2017) = 0` Ta thấy phần trong ngoặc lớn luôn khác `0` ` => (x-2021) * (1/2020 + 1/2019 – 1/2018 – 1/2017) = 0` khi ` x – 2021 = 0` ` \to x = 2021` Vậy ` x= 2021` Bình luận
`(x-1)/2020 + (x-2)/2019=(x-3)/2018 + (x-4)/2017` `<=>(x-1)/2020 + (x-2)/2019-(x-3)/2018 – (x-4)/2017=0` `<=>((x-1)/2020-1) + ((x-2)/2019-1)-((x-3)/2018 -1)-( (x-4)/2017-1)=0` `<=>(x-2021)/2020 + (x-2021)/2019-(x-2021)/2018 – (x-2021)/2017=0` `<=>(x-2021)(1/2020 + 1/2019-1/2018 – 1/2017)=0` `text(vì )1/2020 + 1/2019-1/2018 – 1/2017ne0` `<=>x-2021=0` `<=>x=2021` Bình luận
Đáp án:
` (x-1)/2020 + (x-2)/2019 = (x-3)/2018 + (x-4)/2017`
` => ((x-1)/2020 – 1) + ((x-2)/2019-1) = ((x-3)/2018-1) + ((x-4)/2017-1)`
` => (x-2021)/2020 + (x-2021)/2019 = (x-2021)/2018 + (x-2021)/2017`
` => (x-2021) * (1/2020 + 1/2019 – 1/2018 – 1/2017) = 0`
Ta thấy phần trong ngoặc lớn luôn khác `0`
` => (x-2021) * (1/2020 + 1/2019 – 1/2018 – 1/2017) = 0` khi
` x – 2021 = 0`
` \to x = 2021`
Vậy ` x= 2021`
`(x-1)/2020 + (x-2)/2019=(x-3)/2018 + (x-4)/2017`
`<=>(x-1)/2020 + (x-2)/2019-(x-3)/2018 – (x-4)/2017=0`
`<=>((x-1)/2020-1) + ((x-2)/2019-1)-((x-3)/2018 -1)-( (x-4)/2017-1)=0`
`<=>(x-2021)/2020 + (x-2021)/2019-(x-2021)/2018 – (x-2021)/2017=0`
`<=>(x-2021)(1/2020 + 1/2019-1/2018 – 1/2017)=0`
`text(vì )1/2020 + 1/2019-1/2018 – 1/2017ne0`
`<=>x-2021=0`
`<=>x=2021`