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

Toán Lớp 8: Tính a, $\frac{3x-1}{x+3}$ – $\frac{2x-3}{x+3}$ b, 5x/x^2-2x – 3/x c, x+9/x^2-9 – 3/x^2+3x

Home/ Toán Lớp 8: Tính a, $\frac{3x-1}{x+3}$ – $\frac{2x-3}{x+3}$ b, 5x/x^2-2x – 3/x c, x+9/x^2-9 – 3/x^2+3x

Toán Lớp 8: Tính a, $\frac{3x-1}{x+3}$ – $\frac{2x-3}{x+3}$ b, 5x/x^2-2x – 3/x c, x+9/x^2-9 – 3/x^2+3x

Tháng Bảy 26, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: Tính
a, $\frac{3x-1}{x+3}$ – $\frac{2x-3}{x+3}$
b, 5x/x^2-2x – 3/x
c, x+9/x^2-9 – 3/x^2+3x

Comments ( 2 )

  1. danvanthu
    danvanthu
    26 Tháng Bảy, 2022 at 10:35 chiều
    Reply
    $a) \dfrac{3x-1}{x+3}$ – $\dfrac{2x-3}{x+3}$
    = $\dfrac{(3x-1)-(2x-3)}{x+3}$
    = $\dfrac{3x-1-2x+3}{x+3}$
    = $\dfrac{x+2}{x+3}$ 
    $b)\dfrac{5x}{x^{2}-2x}$ – $\dfrac{3}{x}$
    = $\dfrac{5x}{x.(x-2)}$ – $\dfrac{3}{x}$
    = $\dfrac{5x}{x(x-2)}$ – $\dfrac{3(x-2)}{x(x-2)}$
    = $\dfrac{5x-3(x-2)}{x(x-2)}$
    = $\dfrac{5x – 3x + 6}{x(x-2)}$
    = $\dfrac{2x + 6}{x(x-2)}$
    = $\dfrac{2(x+3)}{x(x-2)}$ 
    $c) \dfrac{x+9}{x^{2}-9}$ – $\dfrac{3}{x^{2}+3x}$
    = $\dfrac{x+9}{(x-3)(x+3)}$ – $\dfrac{3}{x(x+3)}$
    = $\dfrac{x(x+9)}{x(x-3)(x+3)}$ – $\dfrac{3(x-3)}{x(x-3)(x+3)}$
    = $\dfrac{x^{2}+9x-3x+9}{x(x-3)(x+3)}$
    = $\dfrac{x^{2}+6x+9}{x(x-3)(x+3)}$
    = $\dfrac{(x+3)^{2}}{x(x-3)(x+3}$
    = $\dfrac{x+3}{x(x-3)}$

  2. ngoclanhoa
    ngoclanhoa
    26 Tháng Bảy, 2022 at 10:35 chiều
    Reply
    Giải đáp:
    a) {x + 2}/{x + 3}
    b) {2(x + 3)}//{x(x-2)}
    c) {x + 3}/{x(x – 3)}
    Lời giải và giải thích chi tiết:
    a)
    {3x – 1}/{x + 3} – {2x – 3}/{x + 3}
    = {3x – 1 – (2x – 3)}/{x + 3}
    = {3x – 1 – 2x + 3}/{x + 3}
    = {x + 2}/{x + 3}
    b)
    {5x}/{x^2 – 2x} – 3/x
    = {5x}/{x(x – 2)} – 3/x
    = {5x}/{x(x – 2)} – {3(x-2)}/{x(x-2)}
    = {5x}/{x(x – 2)} – {3x-6}/{x(x-2)}
    = {5x – (3x – 6)}/{x(x-2)}
    = {5x – 3x + 6}/{x(x-2)}
    = {2x + 6}//{x(x-2)}
    = {2(x + 3)}//{x(x-2)}
    c)
    {x + 9}/{x^2 – 9} – 3/{x^2 + 3x}
    = {x + 9}/{x^2 – 3^2} – 3/{x(x + 3)}
    ={x + 9}/{(x – 3)(x + 3)} – 3/{x(x + 3)}
    = {x(x + 9)}/{x(x – 3)(x + 3)} – {3(x – 3)}/{x(x + 3)(x-3)}
    = {x^2 + 9x}/{x(x – 3)(x + 3)} – {3x – 9}/{x(x + 3)(x-3)}
    = {x^2 + 9x – (3x – 9)}/{x(x + 3)(x-3)}
    = {x^2 + 9x – 3x + 9}/{x(x + 3)(x-3)}
    = {x^2 + 6x + 9}/{x(x + 3)(x-3)}
    = {x^2 + 2.x.3 + 3^2}/{x(x + 3)(x-3)}
    = (x + 3)^2/{x(x + 3)(x-3)}
    = {x + 3}/{x(x – 3)}
    #SunHee

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

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