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

Toán Lớp 6: `13.` 30 : (x – 7) = 15 `14.` 156 + (x – 61) = 180 `15.` (x – 35) – 120 = 35 `16.` $5^{x}$ + $5^{x+2}$ = 650

Toán Lớp 6: 13. 30 : (x – 7) = 15
14. 156 + (x – 61) = 180
15. (x – 35) – 120 = 35
16. $5^{x}$ + $5^{x+2}$ = 650

Comments ( 2 )

  1. 13.
    30:(x-7)=15
    ⇔x-7=30:15
    ⇔x-7=2
    ⇔x=2+7
    ⇔x=9
    Vậy x=9
    14.
    156+(x-61)=180
    ⇔x-61=180-156
    ⇔x-61=24
    ⇔x=24+61
    ⇔x=85
    Vậy x=85
    15.
    (x-35)-120=35
    ⇔x-35=35+120
    ⇔x-35=155
    ⇔x=155+35
    ⇔x=190
    Vậy x=190
    16.
    5^x +5^(x+2) =650
    ⇔5^x +5x.5^2 =650
    ⇔5^x .(1+5^2) =650
    ⇔5^x .(1+25)=650
    ⇔5^x. 26=650
    ⇔5^x =650:26
    ⇔5^x =25
    ⇔5^x =5^2
    ⇒x=2
    Vậy x=2
    $@Masonn$

  2. 13)30 : (x – 7) = 15
    <=>x-7=2
    <=>x=9
    Vậy x=9
    14)156 + (x – 61) = 180
    <=>x-61=24
    <=>x=85
    Vậy x=85
    15)(x – 35) – 120 = 35
    <=>x-35=155
    <=>x=190
    Vậy x=190
    16)5^x +5^(x+2)=650
    <=>5^x+5^x.5^2=650
    <=>5^x(1+5^2)=650
    <=>5^x . 26=650
    <=>5^x=25
    <=>5^x=5^2
    <=>x=2
    Vậy x=2

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