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

Toán Lớp 8: 1) x+1/ x-2 + x-18/ x-2 + x+2/ x^2-4 2) 2/ x-3 – 6/ x^-9 + 1/ x-3 3) 8/ x^2+4x + 5/ x+4 – 2/ x (đề bà

Toán Lớp 8: 1) x+1/ x-2 + x-18/ x-2 + x+2/ x^2-4
2) 2/ x-3 – 6/ x^-9 + 1/ x-3
3) 8/ x^2+4x + 5/ x+4 – 2/ x (đề bài là thực hiện phép tính ạ )

Comments ( 1 )

  1. Giải đáp:
     
    Lời giải và giải thích chi tiết:
     1,[x+1]/[x-2] +[x-18]/[x-2] +[x+2]/[x^2 -4]
    =([x+1]/[x-2] +[x-18]/[x-2] )+[x+2]/[(x-2)(x+2)]
    =[x+1+x-18]/[x-2] +1/[x-2]
    =[2x-17]/[x-2]+ 1/[x-2]
    =[2x-17+1]/[x-2]
    =[2x-16]/[x-2]
    2, 2/[x-3] -6/[x^2 -9] +1/[x-3]
    =(2/[x-3] +1/[x-3] )-6/[(x-3)(x+3)]
    = 3/[x-3] -6/[(x-3)(x+3)]
    =[3(x+3)]/[(x-3)(x+3)] -6/[(x-3)(x+3)]
    =[3x+9-6]/[(x-3)(x+3)]
    =[3x+3]/[(x-3)(x+3)]
    3,8/[x^2 +4x] +5/[x+4] -2/x
    =8/[x(x+4)]+5/[x+4] -2/x
    =8/[x(x+4)]+[5.x]/[x(x+4)] +[-2(x+4)]/[x(x+4)]
    =[8+5x-2x-8]/[x(x+4)]
    =[3x]/[x(x+4)]
    =3/[x+4]
    (Bài tham khảo)

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

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