Chapter 9: Problem 65
Simplify each expression. $$3 \sqrt{8}-5 \sqrt{20}-7 \sqrt{18}-9 \sqrt{125}$$
Short Answer
Expert verified
The simplified expression is \(-15\sqrt{2} - 55\sqrt{5}\).
Step by step solution
01
Break Down Each Radical
First, let's break down each square root to its simplest radical form. - For \( \sqrt{8} \), we have that 8 can be written as \( 4 \times 2 \). Therefore, \( \sqrt{8} = \sqrt{4 \times 2} = \sqrt{4} \cdot \sqrt{2} = 2\sqrt{2} \).- For \( \sqrt{20} \), 20 can be written as \( 4 \times 5 \). Therefore, \( \sqrt{20} = \sqrt{4 \times 5} = \sqrt{4} \cdot \sqrt{5} = 2\sqrt{5} \).- For \( \sqrt{18} \), 18 can be written as \( 9 \times 2 \). Therefore, \( \sqrt{18} = \sqrt{9 \times 2} = \sqrt{9} \cdot \sqrt{2} = 3\sqrt{2} \).- For \( \sqrt{125} \), 125 can be written as \( 25 \times 5 \). Therefore, \( \sqrt{125} = \sqrt{25 \times 5} = \sqrt{25} \cdot \sqrt{5} = 5\sqrt{5} \).
02
Substitute Simplified Radicals into Original Expression
Now we substitute the simplified radical forms back into the original expression: \( 3 \sqrt{8} - 5 \sqrt{20} - 7 \sqrt{18} - 9 \sqrt{125} \)Revised, it becomes:\( 3(2\sqrt{2}) - 5(2\sqrt{5}) - 7(3\sqrt{2}) - 9(5\sqrt{5}) \)
03
Distribute Coefficients
Next, distribute the coefficients across each term:- \( 3(2\sqrt{2}) = 6\sqrt{2} \)- \( 5(2\sqrt{5}) = 10\sqrt{5} \)- \( 7(3\sqrt{2}) = 21\sqrt{2} \)- \( 9(5\sqrt{5}) = 45\sqrt{5} \)
04
Combine Like Terms
Now, let's combine like terms:We have terms with \( \sqrt{2} \) and terms with \( \sqrt{5} \):- For \( \sqrt{2} \) terms: \( 6\sqrt{2} - 21\sqrt{2} = -15\sqrt{2} \)- For \( \sqrt{5} \) terms: \( -10\sqrt{5} - 45\sqrt{5} = -55\sqrt{5} \)
05
Write Final Answer
The expression after simplification is:\(-15\sqrt{2} - 55\sqrt{5}\)
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Radical Expressions
Radical expressions involve numbers under a square root, cube root, or other root symbols. These expressions can often be simplified using various techniques. To simplify radical expressions, a common approach is to look for factors that are perfect squares in the case of square roots. Breaking down a radical into its simplest form means finding those perfect square factors.
- Identify the largest perfect square factor of the number under the radical.
- Separate this factor while keeping it under the square root.
- Look for additional factors, if possible, and simplify.
Square Roots
Square roots are a type of radical expression where the power of two is involved. The symbol \( \sqrt{} \) denotes a square root and aims to find a number that, when multiplied by itself, results in the original number. Understanding the properties of square roots is key to simplifying and computing expressions effectively.
- A perfect square is a number like 4, 9, 16, etc., that has an integer as its square root.
- For non-perfect squares, simplify by factoring them into smaller components, one of which is a perfect square.
Combining Like Terms
Combining like terms is a fundamental algebraic principle involving the simplification of expressions by unifying similar components. In terms of radical expressions, like terms include expressions that have the same radical component.
- For radicals, this means combining terms that share the same number under the square root.
- This is usually performed after simplifying each of the radicals to their simplest forms.