Chapter 7: Problem 58
Which expression is NOT equal to 13\(?\) A. \((4+\sqrt{3})(4-\sqrt{3})\) C. \((6+\sqrt{23})(6-\sqrt{23})\) B. \((5-2 \sqrt{3})(5+2 \sqrt{3})\) D. \((7-\sqrt{6})(7+\sqrt{6})\)
Short Answer
Expert verified
Option D is not equal to 13.
Step by step solution
01
Simplify Choice A
Simplify the expression \((4+\sqrt{3})(4-\sqrt{3})\). This is in the form of \((a+b)(a-b) = a^2 - b^2\), therefore the simplified expression is \((4)^2 - (\sqrt{3})^2 = 16 - 3 = 13\). So, Choice A equals to 13
02
Simplify Choice C
Next, simplify the expression \((6+\sqrt{23})(6-\sqrt{23})\). By applying the same property of \(a^2 - b^2\), it becomes \((6)^2 - (\sqrt{23})^2 = 36 - 23 = 13\). So, Choice C equals to 13
03
Simplify Choice B
Now, simplify the expression \((5-2 \sqrt{3})(5+2 \sqrt{3})\). Applying the formula, it becomes \((5)^2 - (2 \sqrt{3})^2 = 25 - 12 = 13\). So, Choice B equals to 13
04
Simplify Choice D
Lastly, simplify the expression \((7-\sqrt{6})(7+\sqrt{6})\). Applying the formula, it becomes \((7)^2 - (\sqrt{6})^2 = 49 - 6 = 43\). So, Choice D does not equal to 13 but 43
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Difference of Squares
The difference of squares is a commonly used algebraic identity that helps simplify expressions of the form \((a+b)(a-b)\). This pattern results in \(a^2 - b^2\). Let's consider why this happens. When we expand \((a+b)(a-b)\), we use distributive property:
- First, multiply \(a\) by \(a\) to get \(a^2\).
- Then, multiply \(a\) by \(-b\) to get \(-ab\).
- Next, multiply \(b\) by \(a\) to get \(+ab\).
- Finally, multiply \(b\) by \(-b\) to get \(-b^2\).
Algebraic Expressions
An algebraic expression is a mathematical phrase that can contain numbers, variables, and operation symbols. Consider it a way to represent numbers using symbols and letters. It can be as simple as \( x + 2 \) or as complex as \((3x^2 + 2x - 5)\). Let's break down the components:
- Terms: Parts of the expression separated by '+' or '-' signs.
- Variables: Symbols (often letters) that stand for unknown values.
- Constants: Numbers without variables, like \(2\) or \(5\).
- Coefficients: Numbers that multiply a variable, such as \(3\) in \(3x\).
Radicals
Radicals are expressions that include the root symbol \(\sqrt{}\), which indicates a root of a number. Commonly, you’ll encounter square roots, like \(\sqrt{4}\). Here are some essential points about radicals:
- Square Roots: The most common type is the square root, written as \(\sqrt{x}\), which represents a number that, when multiplied by itself, gives \(x\).
- Radical Simplification: This involves rewriting the radical in its simplest form, such as \(\sqrt{18} = 3\sqrt{2}\).
- Radical Multiplication: Treat radicals like variables when multiplying: \(\sqrt{a} \times \sqrt{b} = \sqrt{ab}\).
Equivalent Expressions
Equivalent expressions are expressions that, although they may look different, have the same value. This concept allows you to rewrite expressions in different forms. For instance, consider \((4+\sqrt{3})(4-\sqrt{3})\) and \(13\). After simplifying using the difference of squares, both expressions equal \(13\).
- Why Are These Important? Because they help in simplifying and solving algebraic equations by transforming complex expressions into more manageable forms.
- Verification: To verify if two expressions are equivalent, simplify each expression as much as possible. If they simplify to the same value, they are equivalent.
- Properties: Equivalent expressions maintain equality even when altered through addition, subtraction, multiplication, or division, provided the operations are performed on both sides equally.