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Mathematics

Assertion (A): (x-1 - y-1) × (x - y)-1 = x-1y-1

Reason (R): For any non-zero number x, x1=1xx,\ x^{-1} = \dfrac{1}{x}

  1. A is true, R is false

  2. A is false, R is true

  3. Both A and R are true

  4. Both A and R are false

Indices

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Answer

Given,

(x-1 - y-1) × (x - y)-1 = x-1y-1

Solving L.H.S,

(x1y1)×(xy)1(1x1y)×(1xy)(yxxy)×1xy(xy)xy×1xy1xyx1y1.\Rightarrow (x^{-1} - y^{-1}) \times (x - y)^{-1} \\[1em] \Rightarrow \Big(\dfrac{1}{x} - \dfrac{1}{y}\Big) \times \Big(\dfrac{1}{x - y}\Big) \\[1em] \Rightarrow \Big(\dfrac{y - x}{xy}\Big) \times \dfrac{1}{x - y} \\[1em] \Rightarrow \dfrac{-(x - y)}{xy} \times \dfrac{1}{x - y} \\[1em] \Rightarrow \dfrac{-1}{xy} \\[1em] \Rightarrow -x^{-1}y^{-1}.

L.H.S ≠ R.H.S

Thus, Assertion (A) is false.

For any non-zero number x, the notation x−1 is defined as its multiplicative inverse, which is equal to 1x\dfrac{1}{x}

Thus, Reason (R) is true.

A is false, R is true

Hence, option 2 is the correct option.

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