“Bài 1 : Tìm `x ` , biết : a ) 123 – 5 (`x ` + 4 ) = 38 b ) [( 6`x ` – 72 ) : 2 – 84 ] . 24 =

“Bài 1 : Tìm `x ` , biết :

a ) 123 – 5 (`x ` + 4 ) = 38

b ) [( 6`x ` – 72 ) : 2 – 84 ] . 24 = 5688

c ) ( 3`x ` – `2^4 ` ) . `7^3 ` = 2 . `7^4 `

d ) ( 4`x ` – `1 )^3 ` = `27^2 `

e ) 720 : [ 45 – ( 5 – 2`x `)^3 ] = `2^3 ` . 5

f ) 2022 + 2 ( `x ` – 1 ) = 2024

2 bình luận về ““Bài 1 : Tìm `x ` , biết : a ) 123 – 5 (`x ` + 4 ) = 38 b ) [( 6`x ` – 72 ) : 2 – 84 ] . 24 =”

  1. Giải đáp:
     a)
    123-5.(x+4)=38
    => 5.(x+4)=123-38
    => 5.(x+4)=85
    => x+4=85:5
    => x+4=17
    => x=17-4
    => x=13
    Vậy x=13
    b)
    [(6x-72):2-84].24=5688
    => (6x-72):2-84=5688:24
    => (6x-72):2-84=237
    => (6x-72):2=321
    => 6x-72=642
    => 6x=714
    => x=119
    Vậy x=119
    c)
    (3x-2^{4}).7^{3}=2.7^{4}
    => (3x-16).1=2.7
    => 3x-16=14
    => 3x=14+16
    => 3x=30
    => x=10
    d)
    (4x-1)^{3}=27^{2}
    => (4x-1)^{3}=729
    => (4x-1)^{3}=9^{3}
    => 4x-1=9
    => 4x=10
    =>x=10:4
    => x=2,5
    Vậy x=2,5
    e)
    720:[45-(5-2x)^{3}]=2^{3}.5
    => 720:[45-(5-2x)^{3}]=40
    => 45-(5-2x)^{3}=720:40
    => 45-(5-2x)^{3}=18
    => (5-2x)^{3}=45-18
    => (5-2x)^{3}=27
    => (5-2x)^{3}=3^{3}
    => 5-2x=3
    => 2x=2
    => x=1
    Vậy x=1
    f)
    2022+2.(x-1)=2024
    => 2.(x-1)=2024-2022
    => 2.(x-1)=2
    => x-1=2:2
    => x-1=1
    =>x=2
    Vậy x=2
     

    Trả lời
  2. làm bài rất lâu vì vậy mong được hay nhất
    a ) 123 – 5 (x + 4 ) = 38
    =>5 (x + 4 ) = 123 -38
    => 5(x+4)=85
    => x+4 = 85 : 5
    => x+4 =17
    => x=17-4
    => x=13
    vậy x=13
    b ) [( 6x  – 72 ) : 2 – 84 ] . 24 = 5688
    =>( 6x  – 72 ) : 2 – 84=5688 : 24
    =>( 6x  – 72 ) : 2 – 84=237
    =>( 6x  – 72 ) : 2 =237+84
    => ( 6x  – 72 ) : 2 =321
    => 6x -72 =321. 2
    => 6x-72=642
    => 6x =714
    => x=119
    vậy x=119
    c, (3x-2^4) . 7^3 = 2. 7^4
    => (3x-2^4) . 7^3 = 2. 2401
    =>(3x-2^4) . 7^3 = 4802
    => (3x-2^4) . 342=4802
    => 3x -2^4 = 4802 : 342
    => 3x-2^4 =14
    => 3x – 16=14
    => 3x=30
    => x=10
    vậy x=10
    d, (4x-1)^3=27^2
    => (4x-1)^3 =729
    => (4x-1)^3=9^3
    => 4x-1=9
    => 4x=10
    => x=5/2
    vậy x=5/2
    e, 720 : [ 45 – (5 -2x)^3 ] =2^3 .5
    =>720 : [ 45 – (5 -2x)^3 ] = 8.5
    =>720 : [ 45 – (5 -2x)^3 ] =40
    => 45 -(5-2x)^3=720 : 40
    => 45 -(5-2x)^3=18
    => (5-2x)^3=45-18
    => (5-2x)^3=27
    =>(5-2x)^3=3^3
    =>5-2x=3
    =>2x=5-3
    =>2x=2
    =>x=1
    vậy x=1
    f, 2022 + 2(x-1)=2024
    =>2(x-1)=2024-2022
    =>2(x-1)=2
    =>x-1=2:2
    =>x-1=1
    =>x=1+1
    =>x=2
    vậy x=2

    Trả lời

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