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

Toán Lớp 8: đề; a)x/x-1+x+3/x^2-1+1/x+1 b) x+10/x-2+x-18/x-2+x-18/x-2+x+2/x^2-4

Tháng Mười Một 16, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: đề; a)x/x-1+x+3/x^2-1+1/x+1
b) x+10/x-2+x-18/x-2+x-18/x-2+x+2/x^2-4

Comments ( 2 )

  1. doanthulan
    doanthulan
    16 Tháng Mười Một, 2022 at 10:44 chiều
    Reply
    Giải đáp + Lời giải và giải thích chi tiết:
    a) x/(x-1)+(x+3)/(x^2-1)+1/(x+1)(xnepm1)
    =x/(x-1)+(x+3)/[(x-1)(x+1)]+1/(x+1)
    =[x(x+1)]/[(x-1)(x+1)]+(x+3)/[(x-1)(x+1)]+(x-1)/[(x-1)(x+1)]
    =(x^2+x+x+3+x-1)/[(x-1)(x+1)]
    =(x^2+3x+2)/[(x-1)(x+1)]
    =[(x+1)(x+2)]/[(x-1)(x+1)]=(x+2)/(x-1)
    b) (x+10)/(x-2)+(x-18)/(x-2)+(x+2)/(x^2-4)(xnepm2)
    =[(x+10)(x+2)]/[(x-2)(x+2)]+[(x-18)(x+2)]/[(x-2)(x+2)]+(x+2)/[(x-2)(x+2)]
    =(x^2+2x+10x+20+x^2+2x-18x-36+x+2)/[(x-2)(x+2)]
    =[(x^2+x^2)+(2x+10x+2x-18x+x)+(20-36+2)]/[(x-2)(x+2)]
    =(2x^2-3x-14)/[(x-2)(x+2)]
    =(2x^2+4x-7x-14)/[(x-2)(x+2)]
    =[2x(x+2)-7(x+2)]/[(x-2)(x+2)]=[(x+2)(2x-7)]/[(x-2)(x+2)]
    =(2x-7)/(x-2).
     

  2. annhocbichchaubich
    annhocbichchaubich
    16 Tháng Mười Một, 2022 at 10:44 chiều
    Reply
    a)
    x/(x – 1) + (x + 3)/(x^2 – 1) + 1/(x + 1) (đk  x \ne ± 1)
    = (x(x + 1))/((x + 1)(x – 1)) + (x + 3)/((x + 1)(x – 1)) + (x – 1)/((x + 1)(x – 1))
    = (x^2 + x + x + 3 + x – 1)/((x + 1)(x – 1))
    = (x^2 + 3x + 2)/((x + 1)(x – 1))
    = (x^2 + x + 2x + 2)/((x + 1)(x – 1))
    = ((x + 1)(x + 2))/((x + 1)(x – 1))
    = (x + 2)/(x – 1)
    b)
    (x + 10)/(x – 2) + (x – 18)/(x – 2) + (x + 2)/(x^2 – 4) (đk  x \ne ± 2)
    = (x + 10 + x – 18)/(x – 2) + (x + 2)/((x + 2)(x – 2))
    = (2x – 8)/(x – 2) + (x + 2)/((x + 2)(x – 2))
    = ((2x – 8)(x + 2))/((x + 2)(x – 2)) + (x + 2)/((x + 2)(x – 2))
    = (2x^2 – 4x – 16 + x + 2)/((x + 2)(x – 2))
    = (2x^2 – 3x – 14)/((x + 2)(x – 2))
    = (2x^2 + 4x – 7x – 14)/((x + 2)(x – 2))
    = ((2x – 7)(x + 2))/((x + 2)(x – 2))
    = (2x – 7)/(x – 2)

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

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