Question:

Find the value of $(7.995)^{1/3}$ correct to four decimal places.

Updated On: Apr 26, 2024
  • $1.9995$
  • $1.9996$
  • $1.9990$
  • $1.9991$
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The Correct Option is B

Solution and Explanation

$\left(7.995\right)^{1/3}=\left(8-0.005\right)^{1/3}$
$=2\left(1-\frac{0.005}{8}\right)^{1/3}$
$=2\left[1+\left(\frac{1}{3}\right)\left(-\frac{0.005}{8}\right)\right]=2\left[1-0.000208\right]$
$=1.9996$
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Concepts Used:

Binomial Theorem

The binomial theorem formula is used in the expansion of any power of a binomial in the form of a series. The binomial theorem formula is 

Properties of Binomial Theorem

  • The number of coefficients in the binomial expansion of (x + y)n is equal to (n + 1).
  • There are (n+1) terms in the expansion of (x+y)n.
  • The first and the last terms are xn and yn respectively.
  • From the beginning of the expansion, the powers of x, decrease from n up to 0, and the powers of a, increase from 0 up to n.
  • The binomial coefficients in the expansion are arranged in an array, which is called Pascal's triangle. This pattern developed is summed up by the binomial theorem formula.