How can you estimate and compare square roots?

Answer 1

Estimating and comparing square roots can be done through several methods. Here are some approaches:

1. Using Perfect Squares:

To estimate a square root, find the two perfect squares it falls between. For example:

• To estimate $\sqrt{50}$:
  • Identify perfect squares: $7^2=49$ and $8^2=64$.
  • Since $50$ is between $49$ and $64$, we know $7<\sqrt{50}<8$.
  • A more refined estimate can be made knowing $50$ is closer to $49$ than to $64$. Thus, $\sqrt{50}\approx 7.1$.

2. Using Averages:

You can average the two bounding perfect square roots to get a better estimate.

For $\sqrt{50}$:

• The initial estimate was between $7$ and $8$.
• Calculate the average: $(7+8)/2=7.5$.
• Check ${7.5}^2=56.25$, so you can adjust: $\sqrt{50}$ is less than $7.5$, leading to a new range $7<\sqrt{50}<7.5$.

3. Using Decimal Approximations:

If you want more precision, you can do some manual calculation or use a calculator:

• For $\sqrt{50}$:
  • You can compute using a calculator that gives $\sqrt{50}\approx 7.071$.

4. Comparison of Square Roots:

To compare two square roots, you can square both of them to eliminate the square root:

• If you want to compare $\sqrt{a}$ and $\sqrt{b}$, check if $a$ or $b$ is larger. For instance, to compare $\sqrt{50}$ and $\sqrt{32}$:
  • Calculate $50>32$.
  • Therefore, $\sqrt{50}>\sqrt{32}$.

Alternatively, if you have similar numbers, you can estimate both square roots and compare them after estimating.

5. Visualizing on a Number Line:

If available, a number line can help visually place the square roots and see which is larger and how far apart they are.

Summary:

Using perfect squares provides an initial estimate, refining with averages helps get closer to the actual value, and squaring the values can help with direct comparisons. For greater accuracy, calculators or numerical methods may be employed.