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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 7: Tìm x biết: x-2013/5+x-2012/6+x-2011/7=x-5/2013+x-6/2012+x-7/2011 Giúp em với!Em cảm ơn nhiều❤️❤️????????????????

Tháng Mười 27, 2022 Toán học 2 Comments 0 views

Toán Lớp 7: Tìm x biết:
x-2013/5+x-2012/6+x-2011/7=x-5/2013+x-6/2012+x-7/2011
Giúp em với!Em cảm ơn nhiều❤️❤️????????????????

Comments ( 2 )

  1. ngoclandiep
    ngoclandiep
    27 Tháng Mười, 2022 at 11:30 sáng
    Reply
    ( x – 2013 )/5 + ( x – 2012 )/6 + ( x – 2011 )/7 = ( x – 5)/2013 + ( x – 6 )/2012 + ( x – 7 )/2011
    ⇔ ( ( x – 2013 )/5 – 1 ) + ( ( x – 2012 )/6 – 1 ) + ( ( x – 2011 )/7 – 1 ) = ( ( x – 5 )/2013 – 1 ) + ( ( x – 6 )/2012 – 1 ) + ( ( x – 7 )/2011 – 1 )
    ⇔ ( x – 2018 )/5 + ( x – 2018 )/6 + ( x – 2018 )/7 = ( x – 2018 )/2013 + ( x – 2018 )/2012 + ( x – 2018 )/2011
    ⇔ ( x – 2018 )/5 + ( x – 2018 )/6 + ( x – 2018 )/7 – ( x – 2018 )/2013 – ( x – 2018 )/2012 – ( x – 2018 )/2011 = 0
    ⇔ ( x – 2018 ) . ( 1/5 + 1/6 + 1/7 – 1/2013 – 1/2012 – 1/2011 ) = 0
    ⇔ x – 2018 = 0
    ⇔ x = 0 + 2018
    ⇔ x = 2018
    Vậy , x = 2018 .

  2. mocmien87
    mocmien87
    27 Tháng Mười, 2022 at 11:29 sáng
    Reply
    Giải đáp:
    \frac{x-2013}{5}+\frac{x+2012}{6}+\frac{x-2011}{7}=\frac{x-5}{2013}+\frac{x-6}{2012}+\frac{x-7}{2011}
    <=> (\frac{x-2013}{5}-1)+(\frac{x+2012}{6}-1)+(\frac{x-2011}{7}-1)=(\frac{x-5}{2013}-1)+(\frac{x-6}{2012}-1)+(\frac{x-7}{2011}-1)
    <=> \frac{x-2018}{5}+\frac{x-2018}{6}+\frac{x-2018}{7}=\frac{x-2018}{2013}+\frac{x-2018}{2012}+\frac{x-2018}{2011}
    <=> \frac{x-2018}{5}+\frac{x-2018}{6}+\frac{x-2018}{7}-\frac{x-2018}{2013}-\frac{x-2018}{2012}-\frac{x-2018}{2011}=0
    <=> (x-2018)(1/5+1/6+1/7-1/2013-1/2012-1/2011)=0
    <=> x-2018=0 (vì 1/5+1/6+1/7-1/2013-1/2012-1/2011 \ne0)
    <=> x=2018
    Vậy x=2018

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222-9+11+12:2*14+14 = ? ( )

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