What is a square root?

So, we have: $\sqrt{X^2} = \sqrt{25}$ and the result is $X=5$.

Now let's explain in more detail the operation we have performed.

• On the left side of the equation, the square root cancels out the squared power (the square root and the squared power are inverse operations, remember?).
• On the right side, we look for the figure or number that, when squared, gives us the result $25$.

There are two numbers that meet these requirements: $5$ and $-5$.

With that said, it's important to remember that the square root of a number will always be positive.

Therefore, to summarize, in the exercise: $X^2=25$ for example, we have two possible answers: $5$ and $-5$.

If we are given the mathematical expression $\sqrt{25}$ the only possible answer will be $5$.

• The only condition that must be met to find a square root is that the number under the square root must be positive.

You cannot find the square root of a negative number, that is, the expression $\sqrt{-25}$ is not correct and has no answer.

On the other hand,

• the result of a square root does not necessarily have to be an integer,

that is, as long as the number under the square root is positive, we can find its square root.

For example: $\sqrt{89527}\approx 299.210$

Simple square roots are based on multiplication tables. Let's see some examples:

$\sqrt{64}$

Solution: The square root, as we have already seen, is the inverse operation of squaring a number. Therefore, we must ask ourselves which number squared, or which number multiplied by itself, will result in $64$.

Given that: $8^2=64$

the answer will be: $\sqrt{64} = 8$

$\sqrt{49}$

Solution: in this case, we also have to ask ourselves what number squared, or what number multiplied by itself, results in $49$.

Given that: $7^2=49$ the answer will be: $\sqrt{49} = 7$

$\sqrt{9}$

Solution: following the same logic, we see that $3^2=9$and, therefore, the answer will be: $\sqrt{9} = 3$.

In this section, we will apply what we have learned so far regarding square roots and see how we can use this information to solve algebraic exercises that include square roots.

An important rule that we must remember when solving these types of exercises is that:

Square roots should be solved first, that is, before any other mathematical operation that is outside of the square root itself.

$10 + \sqrt{81} =$

Solution:

First, we will solve the square root, as it comes before the addition that is outside of it.

Thus, we obtain:

$\sqrt{81} = 9$

Then we continue with the rest of the exercise:

$10+9=19$

Therefore, the result is $10 + \sqrt{81} = 19$

$3 \times \sqrt{16} +8=$

Solution:

This exercise is a bit more complicated. Initially, we must solve the square root, as this operation precedes any other in the exercise.

Thus, we obtain: $\sqrt{16} = 4$

Afterwards, we should approach the exercise like any other math problem: $3 \times 4 +8$.

According to the order of operations in math, multiplication and division come before addition and subtraction. Therefore, the result is: $20$.

The answer to the exercise is: $3 \times \sqrt{16} +8=20$

$\sqrt{36} \div3+\sqrt{81}\times2=$

Solution:

Here we also need to solve the square roots first.

$\sqrt{36}=6$

$\sqrt{81}=9$

We insert the numbers and solve according to the order of operations:

$6\div3+9\times2=2+18=20$

Therefore, the answer is:

$\sqrt{36} \div3+\sqrt{81}\times2=20$