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

Toán Lớp 8: A) 9/x-5-6/x²-25 B) 6x/x+3-3/2x+6

Toán Lớp 8: A) 9/x-5-6/x²-25
B) 6x/x+3-3/2x+6

Comments ( 2 )

  1. a) 9/(x-5)-6/(x^2-25)(xne+-5)
    =9/(x-5)-6/((x-5)(x+5))
    =(9(x+5)-6)/((x-5)(x+5))
    =(9x+45-6)/((x-5)(x+5))
    =(9x+39)/((x-5)(x+5))
    b) (6x)/(x+3)-3/(2x+6)(xne-3)
    =(6x)/(x+3)-3/(2(x+3))
    =(12x-3)/(2(x+3))
     

  2. a, $\frac{9}{x-5}$ – $\frac{6}{x^{2}-25}$
    = $\frac{9}{x-5}$ – $\frac{6}{(x-5)(x+5)}$
    = $\frac{9(x+5)}{(x-5)(x+5)}$ -$\frac{6}{(x-5)(x+5)}$
    =$\frac{9x+45-6}{(x-5)(x+5)}$
    = $\frac{9x+39}{(x-5)(x+5)}$
     b, $\frac{6x}{x+3}$ -$\frac{3}{2x+6}$
    =$\frac{6x}{x+3}$ -$\frac{3}{2(x+3)}$
    =$\frac{12x}{2(x+3)}$ -$\frac{3}{2(x+3)}$
    =$\frac{12x-3}{2(x+3)}$
    =$\frac{3(x-4)}{2(x+3)}$ 

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