Toán Lớp 6: Tìm x
(x-3)^8=(x-3)^5
(x-16)^8=(x-16)^10
(x-2021)^2022=(x-2021)^2020
Leave a reply
Register Now
Login
Lost Password
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Toán Lớp 6: Tìm x
(x-3)^8=(x-3)^5
(x-16)^8=(x-16)^10
(x-2021)^2022=(x-2021)^2020
Comments ( 2 )
(x-3)^8=(x-3)^5
=>(x-3)^8-(x-3)^5=0
=>(x-3)^5 . (x-3)^3-(x-3)^5=0
=>(x-3)^5 . [(x-3)^3-1]=0
=>[((x-3)^5=0),((x-3)^3-1=0):}
=>[(x-3=0),((x-3)^3=1):}
=>[(x=0+3),(x-3=1):}
=>[(x=3),(x=4):}
Vậy x\in{3;4}
b)
(x-16)^8=(x-16)^10
=>(x-16)^8-(x-16)^10=0
=>(x-16)^8-(x-16)^8 . (x-16)^2=0
=>(x-16)^8 . [1-(x-16)^2]=0
=>[((x-16)^8=0),(1-(x-16)^2=0):}
=>[(x-16=0),((x-16)^2=1):}
=>[(x=16),((x-16)^2=(+-1)^2):}
=>[(x=16),([(x-16=1),(x-16=-1):}):}
=>[(x=16),([(x=17),(x=15):}):}
Vậy x\in{15;16;17}
c)
(x-2021)^2022=(x-2021)^2020
=>(x-2021)^2022-(x-2021)^2020=0
=>(x-2021)^2020 . (x-2021)^2-(x-2021)^2020=0
=>(x-2021)^2020 . [(x-2021)^2-1]=0
=>[((x-2021)^2020=0),((x-2021)^2-1=0):}
=>[(x-2021=0),((x-2021)^2=1):}
=>[(x=2021),((x-2021)^2=(+-1)^2):}
=>[(x=2021),([(x-2021=1),(x-2021=-1):}):}
=>[(x=2021),([(x=2022),(x=2020):}):}
Vậy x\in{2020;2021;2022}