By which number should (-1/4)⁻¹ be multiplied so that the product is the…

2023

By which number should (-1/4)⁻¹ be multiplied so that the product is the reciprocal of (-7/4)⁻¹?

  1. A.

    7/16

  2. B.

    16/7

  3. C.

    -16/7

  4. D.

    -7/16

Show answer & explanation

Correct answer: A

For any non-zero rational number a, the exponent −1 gives its multiplicative inverse: a⁻¹ = 1/a. The reciprocal of any number b is the value 1/b, so that b × (1/b) = 1.

  1. (-1/4)⁻¹ is the multiplicative inverse of -1/4, which is -4.

  2. (-7/4)⁻¹ is the multiplicative inverse of -7/4, which is -4/7.

  3. The reciprocal of (-7/4)⁻¹ is the reciprocal of -4/7, which is -7/4 — this is the target product.

  4. Let x be the required number, so (-4) × x = -7/4.

  5. Solving for x: x = (-7/4) ÷ (-4) = 7/16.

Check: (-4) × 7/16 = -28/16 = -7/4, which matches the target product, confirming the value of x.

Hence, (-1/4)⁻¹ must be multiplied by 7/16.

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