Irrational Numbers Math Example 2

Follow the full solution, then compare it with the other examples linked below.

Example 2

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Show that 2\sqrt{2} lies between 1.41.4 and 1.51.5, then estimate it to one decimal place.

Solution

  1. 1
    Compute 1.42=1.961.4^2 = 1.96 and 1.52=2.251.5^2 = 2.25.
  2. 2
    Since 1.96<2<2.251.96 < 2 < 2.25, we have 1.4<2<1.51.4 < \sqrt{2} < 1.5.
  3. 3
    Try 1.412=1.98811.41^2 = 1.9881 and 1.422=2.01641.42^2 = 2.0164. Since 1.9881<2<2.01641.9881 < 2 < 2.0164, 2โ‰ˆ1.4\sqrt{2} \approx 1.4 to one decimal place.

Answer

2โ‰ˆ1.4\sqrt{2} \approx 1.4
Even though irrational numbers have non-terminating, non-repeating decimals, we can approximate them by squeezing them between known rational values.

About Irrational Numbers

An irrational number is a real number that cannot be expressed as a ratio of two integers pq\frac{p}{q}; its decimal expansion goes on forever without repeating any fixed block of digits.

Learn more about Irrational Numbers โ†’

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