Evaluate The Expression For U = 5 U = 5 U = 5 . − 4 U = -4u = − 4 U = □ \square □

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Introduction

In mathematics, evaluating an expression involves substituting a given value for a variable and simplifying the resulting expression. In this article, we will evaluate the expression $-4u$ for $u = 5$. This involves substituting the value of $u$ into the expression and simplifying the result.

Understanding the Expression

The given expression is $-4u$. This is a linear expression, where $-4$ is the coefficient of the variable $u$. To evaluate this expression, we need to substitute the value of $u$ into the expression and simplify the result.

Substituting the Value of $u$

We are given that $u = 5$. To evaluate the expression $-4u$, we need to substitute this value of $u$ into the expression. This involves replacing the variable $u$ with the value $5$.

Evaluating the Expression

Now that we have substituted the value of $u$ into the expression, we can simplify the result. The expression becomes $-4(5)$.

Simplifying the Expression

To simplify the expression $-4(5)$, we need to multiply the coefficient $-4$ by the value $5$. This involves multiplying the numbers and then applying the sign of the coefficient.

Multiplying the Numbers

The product of $-4$ and $5$ is $-20$. This is because $-4$ multiplied by $5$ is equal to $-20$.

Applying the Sign of the Coefficient

The coefficient $-4$ has a negative sign. When we multiply the coefficient by the value $5$, we need to apply the negative sign to the result. This means that the result of the multiplication is $-20$.

Final Answer

The final answer to the expression $-4u$ for $u = 5$ is $-20$.

Conclusion

In this article, we evaluated the expression $-4u$ for $u = 5$. We substituted the value of $u$ into the expression and simplified the result. The final answer to the expression is $-20$.

Frequently Asked Questions

• What is the value of $-4u$ for $u = 5$?
• How do you evaluate the expression $-4u$ for a given value of $u$?
• What is the final answer to the expression $-4u$ for $u = 5$?

Step-by-Step Solution

1. Substitute the value of $u$ into the expression $-4u$.
2. Simplify the expression by multiplying the coefficient by the value.
3. Apply the sign of the coefficient to the result.
4. The final answer to the expression is the result of the simplification.

Example

Evaluate the expression $-3u$ for $u = 2$.

1. Substitute the value of $u$ into the expression $-3u$.
2. Simplify the expression by multiplying the coefficient by the value.
3. Apply the sign of the coefficient to the result.
4. The final answer to the expression is the result of the simplification.

Tips and Tricks

• When evaluating an expression, make sure to substitute the value of the variable correctly.
• Simplify the expression by multiplying the coefficient by the value.
• Apply the sign of the coefficient to the result.
• The final answer to the expression is the result of the simplification.

Related Topics

• Evaluating expressions with variables
• Simplifying linear expressions
• Applying the sign of a coefficient to a result

References

• [1] "Algebra" by Michael Artin
• [2] "Calculus" by Michael Spivak
• [3] "Linear Algebra" by Jim Hefferon
  

Introduction

Evaluating expressions with variables is a fundamental concept in mathematics. In this article, we will answer some frequently asked questions about evaluating expressions with variables.

Q: What is an expression with a variable?

A: An expression with a variable is a mathematical statement that contains a variable, which is a letter or symbol that represents a value. For example, the expression $2x$ is an expression with a variable, where $x$ is the variable.

Q: How do I evaluate an expression with a variable?

A: To evaluate an expression with a variable, you need to substitute the value of the variable into the expression and simplify the result. For example, if you have the expression $2x$ and the value of $x$ is $3$, you would substitute $3$ into the expression to get $2(3)$, which simplifies to $6$.

Q: What is the difference between evaluating an expression and solving an equation?

A: Evaluating an expression involves substituting a value into the expression and simplifying the result, whereas solving an equation involves finding the value of the variable that makes the equation true. For example, if you have the equation $2x = 6$, solving the equation would involve finding the value of $x$ that makes the equation true, whereas evaluating the expression $2x$ would involve substituting a value into the expression and simplifying the result.

Q: How do I handle negative coefficients in expressions?

A: When you have a negative coefficient in an expression, you need to apply the negative sign to the result of the multiplication. For example, if you have the expression $-3x$ and the value of $x$ is $2$, you would substitute $2$ into the expression to get $-3(2)$, which simplifies to $-6$.

Q: Can I evaluate an expression with a variable if I don't know the value of the variable?

A: No, you cannot evaluate an expression with a variable if you don't know the value of the variable. Evaluating an expression with a variable requires knowing the value of the variable, which is used to substitute into the expression.

Q: How do I handle expressions with multiple variables?

A: When you have an expression with multiple variables, you need to substitute the values of all the variables into the expression and simplify the result. For example, if you have the expression $2xy$ and the values of $x$ and $y$ are $3$ and $4$ respectively, you would substitute $3$ and $4$ into the expression to get $2(3)(4)$, which simplifies to $24$.

Q: Can I use a calculator to evaluate expressions with variables?

A: Yes, you can use a calculator to evaluate expressions with variables. However, you need to make sure that the calculator is set to the correct mode and that you are entering the values correctly.

Q: How do I check my work when evaluating expressions with variables?

A: To check your work when evaluating expressions with variables, you can plug in the value of the variable into the original expression and simplify the result. If the result is the same as the answer you got, then your work is correct.

Q: What are some common mistakes to avoid when evaluating expressions with variables?

A: Some common mistakes to avoid when evaluating expressions with variables include:

• Not substituting the value of the variable into the expression
• Not simplifying the expression correctly
• Not applying the negative sign to the result of the multiplication
• Not checking the work

Q: How do I practice evaluating expressions with variables?

A: To practice evaluating expressions with variables, you can try the following:

• Start with simple expressions and gradually move on to more complex ones
• Use online resources or worksheets to practice evaluating expressions with variables
• Ask a teacher or tutor for help if you are struggling
• Practice regularly to build your skills and confidence.