Question bank / Equivalent expressions

Math · Advanced MathMedium

For x>2x > 2, which expression is equivalent to 1x+2+1x−2\frac{1}{x + 2} + \frac{1}{x - 2}?

A

22x\frac{2}{2x}

B

4x2−4\frac{4}{x^2 - 4}

C

2x2−4\frac{2}{x^2 - 4}

D

2xx2−4\frac{2x}{x^2 - 4}

Show answer and explanation

Answer: D

Use the common denominator (x+2)(x−2)=x2−4(x + 2)(x - 2) = x^2 - 4: (x−2)+(x+2)x2−4=2xx2−4\frac{(x - 2) + (x + 2)}{x^2 - 4} = \frac{2x}{x^2 - 4}.

Choice A adds the numerators and adds the denominators, which is not how fractions are added.

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