Equivalent Expressions

SAT Math· difficulty 4/5

Which expression is equivalent to xx11x+2\dfrac{x}{x - 1} - \dfrac{1}{x + 2}?

  • A

    x1(x1)(x+2)\dfrac{x - 1}{(x-1)(x+2)}

  • B

    x2+2x+1(x1)(x+2)\dfrac{x^2 + 2x + 1}{(x-1)(x+2)}

  • C

    x21(x1)(x+2)\dfrac{x^2 - 1}{(x-1)(x+2)}

  • D

    x2+x+1(x1)(x+2)\dfrac{x^2 + x + 1}{(x-1)(x+2)}

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Explanation

Common denominator: x(x+2)(x1)(x1)(x+2)=x2+2xx+1(x1)(x+2)=x2+x+1(x1)(x+2)\dfrac{x(x+2) - (x-1)}{(x-1)(x+2)} = \dfrac{x^2 + 2x - x + 1}{(x-1)(x+2)} = \dfrac{x^2 + x + 1}{(x-1)(x+2)}.

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