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

Toán Lớp 8: d) (3x – 5)(7 – 5x) – (5x + 2)(2 – 3x) = 4 g) 3(2x – 1)(3x – 1) – (2x – 3)(9x – 1) =0 j) (2x – 1)(3x + 1) – (4 – 3x)(3 – 2x) = 3 k) (2x

Tháng Mười Hai 6, 2022 Toán học 1 Comment 0 views

Toán Lớp 8: d) (3x – 5)(7 – 5x) – (5x + 2)(2 – 3x) = 4
g) 3(2x – 1)(3x – 1) – (2x – 3)(9x – 1) =0
j) (2x – 1)(3x + 1) – (4 – 3x)(3 – 2x) = 3
k) (2x + 1)(x + 3) – (x – 5)(7 + 2x) = 8
m) 2(3x – 1)(2x + 5) – 6(2x – 1)(x + 2) = – 6

Comments ( 1 )

  1. maingocquynhnhu2k1
    maingocquynhnhu2k1
    6 Tháng Mười Hai, 2022 at 1:46 chiều
    Reply
    d)(3x-5)(7-5x)-(5x+2)(2-3x)=4
    ⇔21x-15x²-35+25x-(10x-15x²+4-6x)=4
    ⇔21x-15x²-35+25x-10x+15x²-4+6x=4
    ⇔(-15x²+15x²)+(21x+25x-10x+6x)-(35+4)=4
    ⇔42x-39=4
    ⇔42x=4+39
    ⇔42x=43
    ⇔x=43/42
    Vậy x=43/42
    g)3(2x-1)(3x-1)-(2x-3)(9x-1)=0
    ⇔(6x-3)(3x-1)-(18x²-2x-27x+3)=0
    ⇔18x²-6x-9x+3-18x²+2x+27x-3=0
    ⇔(18x²-18x²)+(-6x-9x+2x+27x)+(3-3)=0
    ⇔14x=0
    ⇔x=0
    Vậy x=0
    j)(2x-1)(3x+1)-(4-3x)(3-2x)=3
    ⇔6x²+2x-3x-1-(12-8x-9x+6x²)=3
    ⇔6x²+2x-3x-1-12+8x+9x-6x²=3
    ⇔(6x²-6x²)+(2x-3x+8x+9x)+(-1-12)=3
    ⇔16x-13=3
    ⇔16x=3+13
    ⇔16x=16
    ⇔x=16:16
    ⇔x=1
    Vậy x=1
    k)(2x+1)(x+3)-(x-5)(7+2x)=8
    ⇔2x²+6x+x+3-(7x+2x²-35-10x)=8
    ⇔2x²+6x+x+3-7x-2x²+35+10x=8
    ⇔(2x²-2x²)+(6x+x-7x+10x)+(3+35)=8
    ⇔10x+38=8
    ⇔10x=8-38
    ⇔10x=-30
    ⇔x=(-30):10
    ⇔x=-3
    Vậy x=-3
    m)2(3x-1)(2x+5)-6(2x-1)(x+2)=-6
    ⇔(6x-2)(2x+5)-6(2x²+4x-x-2)=-6
    ⇔12x²+30x-4x-10-12x²-24x+6x+12=-6
    ⇔(12x²-12x²)+(30x-4x-24x+6x)+(-10+12)=-6
    ⇔8x+2=-6
    ⇔8x=-6-2
    ⇔8x=-8
    ⇔x=(-8):8
    ⇔x=-1
    Vậy x=-1

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

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