How to Estimate Negative and Positive Square Roots
A square root of a number \(n\) is a value that, when multiplied by itself, gives the number \(n\). Every positive real number has two square roots. One is positive, and the other is negative. For instance, the positive square root of \(9\) is \(3\) (because \(3\times3=9\)) and the negative square root is \(-3\) (because \(-3\times-3=9\)).
If the number is negative, it has no real square roots, only complex ones, because there's no real number that you can multiply by itself to get a negative number.
A Step-by-step Guide to Estimating Negative and Positive Square Roots
Here is a step-by-step guide on how to estimate square roots:
Type the problems from this lesson and check each step.
Positive Square Roots
Step 1: Identify the number Let’s say you need to estimate the square root of a number, for instance, \(20\).
Step 2: Find two perfect squares it falls between The square root of \(20\) falls between the square roots of the perfect squares \(16\) \((4\times4)\) and \(25\) \((5\times5)\). So, \(4\) and \(5\) are our lower and upper estimates, respectively.
Step 3: Determine the closer square Is \(20\) closer to \(16\) or \(25\)? Since it’s closer to \(16\), we can say that the square root of \(20\) is slightly more than \(4\).
Negative Square Roots
The negative square root is simply the negative value of the positive square root. So, in our example, the positive square root of \(20\) was slightly more than \(4\), so the negative square root is slightly less than \(-4\).
For more precise estimations, you can use a calculator or mathematical software. Note that the method above only gives an approximate value. In reality, the square root of \(20\) is around \(4.47\) (for the positive root) and \(-4.47\) (for the negative root).
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