Multiply Square Roots: Solving √7 × √7

Question

Solve the following exercise:

77= \sqrt{7}\cdot\sqrt{7}=

Video Solution

Solution Steps

00:00 Solve
00:03 Root of a number (A) times the root of another number (B)
00:07 Equals the root of their product (A times B)
00:11 Let's use this formula in our exercise, and calculate the product
00:14 Let's calculate the root of 49
00:17 And this is the solution to the question

Step-by-Step Solution

In order to simplify the given expression, we will use two laws of exponents:

a. The definition of root as an exponent:

an=a1n \sqrt[n]{a}=a^{\frac{1}{n}} b. The law of exponents for multiplication between terms with identical bases:

aman=am+n a^m\cdot a^n=a^{m+n}

Let's start by converting the square roots to exponents using the law mentioned in a:

77=712712= \sqrt{7}\cdot\sqrt{7}= \\ \downarrow\\ 7^{\frac{1}{2}}\cdot7^{\frac{1}{2}}= We'll continue, since we are multiplying two terms with identical bases - we'll use the law of exponents mentioned in b:

712712=712+12=71=7 7^{\frac{1}{2}}\cdot7^{\frac{1}{2}}= \\ 7^{\frac{1}{2}+\frac{1}{2}}=\\ 7^1=\\ \boxed{7} Therefore, the correct answer is answer a.

Answer

7 7