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

Toán Lớp 8: tìm x : a,x^2+4=4x b,4x^2 =4x-1 c,4x^2 -27=0

Tháng Mười 22, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: tìm x : a,x^2+4=4x
b,4x^2 =4x-1
c,4x^2 -27=0

Comments ( 2 )

  1. haianhtu97
    haianhtu97
    22 Tháng Mười, 2022 at 5:43 chiều
    Reply
    Tìm x:
    a) x^2 + 4 = 4x
    -> x^2 + 4 – 4x = 0
    -> x^2 + 2×2 – 2 = 0
    -> (x-2)^2 = 0
    -> x – 2 = 0
    -> x = 0+2
    -> x = 2 
    b) 4x^2 =4x-1
    -> 4x^2 – (4x -1) = 0
    -> 4x^2 – 4x + 1 = 0
    -> 4x^2 – 2x – 2x + 1 = 0
    -> 2x(2x – 1) – 1(2x – 1) = 0
    -> (2x – 1) (2x-1) = 0
    -> (2x- 1)^2 = 0
    -> 2x – 1 = 0
    -> 2x = 0+1
    -> 2x = 1
    -> x = 1/2
    c)4x^2 -27=0
    -> 4x^2 = 0+27
    -> 4x^2 = 27
    -> x^2 = 27/4
    -> x = $\dfrac{\sqrt{27}}{2}$

  2. hienthucthu97
    hienthucthu97
    22 Tháng Mười, 2022 at 5:43 chiều
    Reply
    a,x^2+4=4x
    x^2-4x+4=0
    (x-2)^2=0
    x-2=0
    x=2
    b,4x^2=4x-1
    4x^2-4x+1=0
    (2x-1)^2=0
    2x-1=0 
    2x=1
    x=1/2
    c,4x^2-27=0
    4x^2=27
    x^2=27/4
    x=(căn27) /2

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

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