Chapter 1: Problem 16
Evaluate each expression for ( \(\boldsymbol{a}\) ) \(x=4\) and \((\boldsymbol{b}) x=6\). \(5 x^{2}\)
Short Answer
Expert verified
For \(x=4\), the result is 80. For \(x=6\), the result is 180.
Step by step solution
01
Understand the expression
The given expression is a mathematical formula: \(5x^2\). This means we need to multiply 5 by the square of \(x\).
02
Step 1a: Substitute \(x = 4\)
First, substitute \(x = 4\) into the expression: \(5(4)^2\).
03
Step 1b: Calculate \(4^2\)
Next, calculate the square of 4: \(4^2 = 16\).
04
Step 1c: Multiply by 5
Finally, multiply 16 by 5: \(5 \times 16 = 80\). Thus, the expression evaluated for \(x = 4\) is 80.
05
Step 2a: Substitute \(x = 6\)
Now, substitute \(x = 6\) into the expression: \(5(6)^2\).
06
Step 2b: Calculate \(6^2\)
Next, calculate the square of 6: \(6^2 = 36\).
07
Step 2c: Multiply by 5
Finally, multiply 36 by 5: \(5 \times 36 = 180\). Thus, the expression evaluated for \(x = 6\) is 180.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Substitution
Substitution is one of the most fundamental concepts in algebra. It involves replacing a variable with a given number or value. For example, in the expression \(5x^2\), if we are given \(x = 4\), we substitute 4 wherever there is an x in the expression. So, \(5x^2\) becomes \(5(4)^2\). This method helps us convert algebraic expressions into numerical computations, making it easier to evaluate them.
Here are some important points to consider for substitution:
Here are some important points to consider for substitution:
- Identify the variable in the expression.
- Replace every occurrence of the variable with the given number.
- Ensure that you maintain the structure of the expression while substituting.
Squaring a Number
Squaring a number means multiplying that number by itself. It is a basic operation in algebra. For instance, squaring 4 gives us \(4 \times 4 = 16\). In our expression \(5x^2\), once we substitute \(x\) with 4, we need to square the 4:
\( (4)^2 = 16 \).
This is because any number raised to the power of 2 is multiplied by itself. Another example is squaring 6:
\((6)^2 = 36\).
The squaring operation is crucial when dealing with quadratic expressions. Remember these key points about squaring:
\( (4)^2 = 16 \).
This is because any number raised to the power of 2 is multiplied by itself. Another example is squaring 6:
\((6)^2 = 36\).
The squaring operation is crucial when dealing with quadratic expressions. Remember these key points about squaring:
- Ensure you multiply the number by itself, not by any other number.
- Squaring a negative number will result in a positive number, as multiplying two negative numbers yields a positive.
- Double-check your calculations to avoid errors.
Multiplication
Multiplication is the arithmetic operation of scaling one number by another. After substituting the variable and squaring the number in the expression \(5x^2\), the next step involves multiplication. For example, once we have \(4^2 = 16\), in the expression \(5(4)^2\), we need to multiply 5 by 16:
\(5 \times 16 = 80\).
This operation combines two quantities to produce a product. Let's see another example where \(x = 6\):
First, square the 6:
\(6^2 = 36\).
Then, multiply by 5:
\(5 \times 36 = 180\).
Key points about multiplication to keep in mind:
\(5 \times 16 = 80\).
This operation combines two quantities to produce a product. Let's see another example where \(x = 6\):
First, square the 6:
\(6^2 = 36\).
Then, multiply by 5:
\(5 \times 36 = 180\).
Key points about multiplication to keep in mind:
- Ensure you are multiplying the correct numbers in sequence.
- Understand that multiplication is associative, meaning \((a \times b) = (b \times a)\).
- Use multiplication properties, such as distributive property, for more complex expressions.