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

Toán Lớp 8: 6) 4(x-1)(x+2) – 5(x+7) = (2x+3)²- 5x + 3 7) (x+5)(x-5) – (x+3)(x² – 3x+9) = 5 – x(x² – x-2) 8) (x-1)(x² + x+1) + 3(x-2

Home/ Toán Lớp 8: 6) 4(x-1)(x+2) – 5(x+7) = (2x+3)²- 5x + 3 7) (x+5)(x-5) – (x+3)(x² – 3x+9) = 5 – x(x² – x-2) 8) (x-1)(x² + x+1) + 3(x-2

Toán Lớp 8: 6) 4(x-1)(x+2) – 5(x+7) = (2x+3)²- 5x + 3 7) (x+5)(x-5) – (x+3)(x² – 3x+9) = 5 – x(x² – x-2) 8) (x-1)(x² + x+1) + 3(x-2

Tháng Hai 16, 2023 Toán học 2 Comments 0 views

Toán Lớp 8: 6) 4(x-1)(x+2) – 5(x+7) = (2x+3)²- 5x + 3
7) (x+5)(x-5) – (x+3)(x² – 3x+9) = 5 – x(x² – x-2)
8) (x-1)(x² + x+1) + 3(x-2)² = x(x² + 3x- 1)
Giải các pt sau hộ e với
5sao+TLHN+Cám ơn

Comments ( 2 )

  1. phuongthuydung
    phuongthuydung
    16 Tháng Hai, 2023 at 11:48 chiều
    Reply
    6
    4(x-1)(x+2)-5(x+7)=(2x+3)^2-5x+3
    ⇔(4x-4)(x+2)-5x-35=4x^2+12x+9-5x+3
    ⇔4x^2+8x-4x-8-5x-35=4x^2+12x+9-5x+3
    ⇔4x^2+8x-4x-5x-4x^2-12x+5x=9+3+8+35
    ⇔(4x^2-4x^2)+(8x-4x-5x-12x+5x)=55
    ⇔-8x=55
    ⇔x=-55/8
    Vậy S={-55/8} 
    7
    (x+5)(x-5)-(x+3)(x^2-3x+9)=5-x(x^2-x-2)
    ⇔x^2-25-(x^3+27)=5-x^3+x^2+2x
    ⇔x^2-25-x^3-27=5-x^3+x^2+2x
    ⇔x^2-x^3+x^3-x^2-2x=5+25+27
    ⇔(x^2-x^2)+(-x^3+x^3)-2x=57
    ⇔-2x=57
    ⇔x=-57/2
    Vậy S={-57/2}
    8
    (x-1)(x^2+x+1)+3(x-2)^2=x(x^2+3x-1)
    ⇔x^3-1+3(x^2-4x+4)=x^3+3x^2-x
    ⇔x^3-1+3x^2-12x+12=x^3+3x^2-x
    ⇔x^3+3x^2-12x-x^3-3x^2+x=-12+1
    ⇔(x^3-x^3)+(3x^2-3x^2)+(-12x+x)=-11
    ⇔-11x=-11
    ⇔x=1
    Vậy S={1}

  2. lanthuhoa
    lanthuhoa
    16 Tháng Hai, 2023 at 11:47 chiều
    Reply
    6)
    4(x-1)(x+2)  – 5(x+7) = (2x+3)^2- 5x + 3
    <=>4(x^2+x-2)-5x-35=4x^2+12x+9-5x+3
    <=>4x^2+4x-8-5x-35=4x^2+7x+12
    <=>4x^2-x-43=4x^2+7x+12
    <=>-x-7x=12+43
    <=>-8x=55
    <=>x=-55/8
    Vậy S={-55/8}
    7)
    (x+5)(x-5) – (x+3)(x^2 – 3x+9) = 5 – x(x^2 – x-2)
    <=>x^2-25-x^3-27=5-x^3+x^2+2x
    <=>-x^3+x^2-52=-x^3+x^2+2x+5
    <=>-x^3+x^3+x^2-x^2-2x-52-5=0
    <=>-2x-57=0
    <=>x=-57/2
    Vậy S={-57/2}
    8)
    (x-1)(x^2+x+1)+3(x-2)^2=x(x^2+3x-1)
    <=>x^3-1+3x^2-12x+12=x^3+3x^2-x
    <=>x^3+3x^2-12x+11=x^3+3x^2-x
    <=>x^3-x^3+3x^2-3x^2-12x+x+11=0
    <=>-11x=-11
    <=>x=1
    Vậy S={1}
     

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

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