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

Toán Lớp 8: Bài 2: Tìm x: a) (x – 3) ² + x (1 – x) = 3 b) 4x (x – 2) – (2x – 1) (2x + 3) = 0 c) (x – 3) ² – (x – 4) (x + 4) = 0 d) (x + 1) ² – (2

Home/ Toán Lớp 8: Bài 2: Tìm x: a) (x – 3) ² + x (1 – x) = 3 b) 4x (x – 2) – (2x – 1) (2x + 3) = 0 c) (x – 3) ² – (x – 4) (x + 4) = 0 d) (x + 1) ² – (2

Toán Lớp 8: Bài 2: Tìm x: a) (x – 3) ² + x (1 – x) = 3 b) 4x (x – 2) – (2x – 1) (2x + 3) = 0 c) (x – 3) ² – (x – 4) (x + 4) = 0 d) (x + 1) ² – (2

Tháng Bảy 18, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: Bài 2: Tìm x:
a) (x – 3) ² + x (1 – x) = 3
b) 4x (x – 2) – (2x – 1) (2x + 3) = 0
c) (x – 3) ² – (x – 4) (x + 4) = 0
d) (x + 1) ² – (2 – x) ² = 4

Comments ( 2 )

  1. tonhu12
    tonhu12
    18 Tháng Bảy, 2022 at 9:56 chiều
    Reply
    Giải đáp:
    a)x=6/5
    b)x=1/4
    c)x=25/6
    d)x=7/6
    Lời giải và giải thích chi tiết:
    a)(x-3)^2+x(1-x)=3
    ⇔x^2-2.x.3+3^2+x-x^2=3
    ⇔x^2-6x+9+x-x^2=3
    ⇔(x^2-x^2)+(-6x+x)=3-9
    ⇔-5x=-6
    ⇔x=(-6)/(-5)
    ⇔x=6/5
    Vậy x=6/5
    b)4x(x-2)-(2x-1)(2x+3)=0
    ⇔4x^2-8x-(4x^2+6x-2x-3)=0
    ⇔4x^2-8x-4x^2-6x+2x+3=0
    ⇔(4x^2-4x^2)+(-8x-6x+2x)+3=0
    ⇔-12x+3=0
    ⇔-12x=-3
    ⇔x=(-3)/(-12)
    ⇔x=1/4
    Vậy x=1/4
    c)(x-3)^2-(x-4)(x+4)=0
    ⇔x^2-2.x.3+3^2-(x^2-4^2)=0
    ⇔x^2-6x+9-x^2+4^2=0
    ⇔x^2-6x+9-x^2+16=0
    ⇔(x^2-x^2)+(9+16)-6x=0
    ⇔25-6x=0
    ⇔6x=25
    ⇔x=(25)/6
    Vậy x=25/6
    d)(x+1)^2-(2-x)^2=4
    ⇔x^2+2x.1+1^2-(2^2-2.2.x+x^2)=4
    ⇔x^2+2x+1-(4-4x+x^2)=4
    ⇔x^2+2x+1-4+4x-x^2=4
    ⇔(x^2-x^2)+(2x+4x)=4+4-1
    ⇔6x=7
    ⇔x=7/6
    Vậy x=7/6

  2. minhtuquynh
    minhtuquynh
    18 Tháng Bảy, 2022 at 9:56 chiều
    Reply
    a) (x – 3) ² + x (1 – x) = 3
    => x² – 6x + 9 + x – x² – 3 = 0
    => -5x + 6 = 0
    => -5x = -6
    => x = 6/5
    Vậy x = 6/5
    b) 4x (x – 2) – (2x – 1) (2x + 3) = 0
    => 4x² – 8x – (4x² + 6x – 2x – 3) = 0
    => 4x² – 8x – 4x² – 6x + 2x + 3 = 0
    => -12x + 3 = 0
    => -12x = -3
    => x = 1/4
    Vậy x = 1/4
    c) (x – 3) ² – (x – 4) (x + 4) = 0
    => x² – 6x + 9 – x² + 16 = 0
    => -6x + 25 = 0
    => -6x = -25
    => x = 25/6
    Vậy x = 25/6
    d) (x + 1) ² – (2 – x) ² = 4
    => (x + 1 + 2 – x) (x + 1 – 2 + x) = 4
    => 3 (2x – 1) = 4
    => 2x – 1 = 4/3
    => 2x = 7/3
    => x = 7/6
    Vậy x = 7/6

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

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