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

Toán Lớp 8: Bài 7: thực hiện phép tính như sau: a, $\frac{4-2x}{x^2-4}$+$\frac{2x}{x-2}$+$\frac{-x}{x+2}$ b, $\frac{1}{x+1}$+$\frac{x}{x-1}$+$\fra

Tháng Tư 29, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: Bài 7: thực hiện phép tính như sau:
a, $\frac{4-2x}{x^2-4}$+$\frac{2x}{x-2}$+$\frac{-x}{x+2}$
b, $\frac{1}{x+1}$+$\frac{x}{x-1}$+$\frac{2}{x^2-1}$
c, $\frac{3}{2x}$+$\frac{3x-3}{2x-1}$+$\frac{2x^2+1}{4x^2-2x}$
giúp mik vs
mik vote 5 sao cho

Comments ( 2 )

  1. ngoclanquynh
    ngoclanquynh
    29 Tháng Tư, 2022 at 3:27 chiều
    Reply
    a) (4-2x)/(x^2-4) + (2x)/(x-2) + (-x)/(x+2)
    = [4-2x+2x.(x+2)-x.(x-2)]/[(x-2).(x+2)]
    = (4-2x+2x^2+4x-x^2+2x)/[(x-2).(x+2)]
    = (x^2+2x)/[(x-2).(x+2)]
    = [x.(x+2)]/[(x-2).(x+2)]
    = x/(x-2)
    b) 1/(x+1) + x/(x-1) + 2/(x^2 -1)
    = [1.(x-1)+x.(x+1)-2)]/[(x+1).(x-1)]
    = (x-1+x^2+x-2)/[(x+1).(x-1)]
    = (x^2 + 2x – 3)/[(x+1).(x-1)]
    = [(x-1).(x+3)]/[(x+1).(x-1)]
    = (x+3)/(x+1)
    c) 3/(2x) + (3x-3)/(2x-1) + (2x^2+1)/(4x^2-2x)
    = [3.(2x-1)+(3x-3).2x+2x^2+1]/[2x.(2x-1)]
    = (6x-3+6x^2-6x+2x^2+1)/[2x.(2x-1)]
    = (8x^2-2)/[2x.(2x-1)]
    = [2.(4x^2-1)]/[2x.(2x-1)]
    = [2.(2x-1).(2x+1)]/[2x.(2x-1)]
    = (2x+1)/x
    – Áp dụng hằng đẳng thức: A^2 – B^2 = (A-B).(A+B)
     

  2. hauthanhyen98
    hauthanhyen98
    29 Tháng Tư, 2022 at 3:27 chiều
    Reply
    Bài 7: thực hiện phép tính như sau:
    a) $\frac{4-2x}{x^2-4}$+$\frac{2x}{x-2}$+$\frac{-x}{x+2}$
    =$\frac{4-2x}{(x-2)(x+2)}$+$\frac{2x.(x+2)}{(x-2)(x+2)}$+$\frac{-x(x-2)}{(x+2)(x-2)}$
    =$\frac{4-2x+2x^2+4x-x^2+2x}{(x-2)(x+2)}$
    =$\frac{x^2+4x+4}{(x-2)(x+2)}$
    =$\frac{(x+2)^2}{(x-2)(x+2)}$
    =$\frac{(x+2)^2}{x-2}$
    b)$\frac{1}{x+1}$+$\frac{x}{x-1}$+$\frac{2}{x^2-1}$
    =$\frac{1(x-1)}{(x+1)(x-1)}$+$\frac{x(x+1)}{(x-1)(x+1)}$+$\frac{2}{(x-1)(x+1)}$
    =$\frac{x-1+x^2+x+2}{(x+1)(x-1)}$
    =$\frac{x^2+2x+1}{(x+1)(x-1)}$
    =$\frac{(x+1)^2}{(x+1)(x-1)}$
    =$\frac{(x+1)}{(x-1)}$
    c) $\frac{3}{2x}$+$\frac{3x-3}{2x-1}$+$\frac{2x^2+1}{4x^2-2x}$
    =$\frac{6x-3+6x^2-6x+2x^2+1}{2x(2x-1)}$
    =$\frac{8x^2-2}{2x(2x-1)}$
    =$\frac{2(4x^2-1)}{2x(2x-1)}$
    =$\frac{2(2x-1)(2x+1)}{2x(2x-1)}$
    =$\frac{2x+1}{x}$

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

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