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

Toán Lớp 8: Thực Hiện Phép TÍnh e. 1/x+2 + 1/ (x+2)(3x+5) f. 1/x-1 +2/x+1 + 3-x/ x2-1

Tháng Bảy 25, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: Thực Hiện Phép TÍnh
e. 1/x+2 + 1/ (x+2)(3x+5)
f. 1/x-1 +2/x+1 + 3-x/ x2-1

Comments ( 2 )

  1. minhtuyethue
    minhtuyethue
    25 Tháng Bảy, 2022 at 3:59 chiều
    Reply
    $\frac{1}{x+2}$ + $\frac{1}{(x+2)(3x+5)}$
    = $\frac{(3x+5)}{(x+2).(3x+5)}$ + $\frac{1}{(x+2)(3x+5)}$
    =$\frac{3x+6}{(x+2).(3x+5)}$
    =$\frac{3.(x+2)}{(x+2).(3x+5)}$
    =$\frac{3}{(3x+5)}$
    $\frac{1}{x-1}$ +$\frac{2}{x+1}$ + $\frac{3-x}{x^2-1}$
    =$\frac{x+1}{x^2-1}$ + $\frac{2.(x-1)}{x^2-1}$ + $\frac{3-x}{x^2-1}$
    =$\frac{x+1+2x-2+3-x}{x^2-1}$
    =$\frac{2x+2}{x^2-1}$
    =$\frac{2.(x+1)}{(x+1).(x-1)}$
    =$\frac{2}{x-1}$  

  2. haianhtu97
    haianhtu97
    25 Tháng Bảy, 2022 at 3:59 chiều
    Reply
    e) 1/(x+2) + 1/[(x+2)(3x+5)]
    = (3x+5)/[(3x+5)(x+2)] + 1/[(x+2)(3x+5)]
    = (3x+5+1)/[(3x+5)(x+2)]
    = (3x+6)/[(3x+5)(x+2)]
    = [3(x+2)]/[(3x+5)(x+2)]
    = 3/(3x+5)
    f) 
    1/(x-1) + 2/(x+1) + (3-x)/(x^2-1)
    = (x+1)/[(x-1)(x+1)] + [2(x-1)]/[(x-1)(x+1)] + (3-x)/[(x-1)(x+1)]
    = (x+1 + 2x-2 + 3-x)/[(x-1)(x+1)]
    = (2x +2)/[(x-1)(x+1)]
    = [2(x+1)]/[(x-1)(x+1)]
    = 2/(x-1)
     

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

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