Chapter 8: Problem 34
Simplify. $$\sqrt{20}+\sqrt{80}-\sqrt{125}$$
Short Answer
Expert verified
The simplified result is \( \sqrt{5}\).
Step by step solution
01
Prime Factorize All Numbers Under The Square Roots
Find the prime factorisation of each number underneath the root: \(20 = 2^2 × 5\), \(80 = 2^4 × 5\), and \(125 = 5^3\).
02
Simplify The Square Roots
For each number under the root, bring out the multiples of 2 from under the root sign: \(\sqrt{20} = 2\sqrt{5}\), \(\sqrt{80} = 2^2\sqrt{5} = 4\sqrt{5}\), and \(\sqrt{125} = 5\sqrt{5}\).
03
Perform the Addition and Subtraction of Square Roots
Now, add the simplified square roots and subtract the simplified square roots: \(2\sqrt{5} + 4\sqrt{5} - 5\sqrt{5}\).
04
Combine Like Terms
Combine the like terms to get the final answer: \( (2 + 4 - 5)\sqrt{5} = \sqrt{5}\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Prime Factorization
Prime factorization involves breaking down a number into its prime numbers, which are numbers only divisible by 1 and themselves. For instance, when you are given a number like 20, the process involves finding the smallest prime number that divides it perfectly. The prime factors of 20 are 2 and 5 since 20 can be broken down into \( 2^2 \times 5 \). This helps in simplifying square roots.
- Identify the smallest prime number that divides the number.
- Divide the entire number by this prime number.
- Repeat the process with the quotient until only prime numbers are left.
Square Roots
The square root of a number is a value that, when multiplied by itself, gives the original number. For example, the square root of 9 is 3 because \(3 \times 3 = 9\). With prime factorization, simplifying square roots becomes easier.
- Simplification: Once you have the prime factorization, you can simplify the square root by "bringing out" pairs of prime numbers. Each pair represents a perfect square that can be taken outside the square root.
- Example: In \( \sqrt{80} \), the prime factorization is \( 2^4 \times 5 \). You can take \( 2^2 \) out of the square root because \( 4 \) is a perfect square: \( 4 \sqrt{5} \).
Combining Like Terms
Combining like terms is a fundamental algebraic process where similar terms are added or subtracted to simplify expressions. This concept is essential when working with radicals, especially after simplifying them.
- Like Terms: These are terms that have the same variable raised to the same power, such as \( 2 \sqrt{5} \) and \( 4 \sqrt{5} \). Only like terms can be combined.
- Combining: This involves adding or subtracting the coefficients (the numbers in front of the radicals) while keeping the radical unchanged. In \( 2\sqrt{5} + 4\sqrt{5} - 5\sqrt{5} \), the terms are combined as follows: \((2+4-5)\sqrt{5} \).
- Final Result: The expression simplifies to \( \sqrt{5} \), as the addition and subtraction of the coefficients \( (2+4-5) = 1 \) lead to this final term.