Multiplying Both Sides of the Equation

Oct 13, 2025 by wbrum.org 49 views

Introduction

In mathematics, linear equations are a fundamental concept that plays a crucial role in various branches of mathematics, science, and engineering. Solving linear equations involves manipulating the equations to isolate the variable(s) and find the solution. One of the techniques used to solve linear equations is multiplying both sides of the equation by a constant. In this article, we will explore how to multiply both sides of the equation by a constant and apply this concept to solve a given equation.

The Given Equations

We are given two linear equations:

${ 4y + 3x = -6 }$

${ y - x = -5 }$

Our goal is to multiply both sides of the second equation by a constant and choose the correct option.

Multiplying Both Sides of the Equation

To multiply both sides of the equation by a constant, we need to follow the distributive property of multiplication over addition. The distributive property states that for any real numbers a, b, and c:

${ a(b + c) = ab + ac }$

Using this property, we can multiply both sides of the equation by a constant.

Option A: Multiplying by 2

Let's multiply both sides of the equation by 2:

${ 2(y - x) = 2(-5) }$

Using the distributive property, we get:

${ 2y - 2x = -10 }$

Option B: Multiplying by 3

Next, let's multiply both sides of the equation by 3:

${ 3(y - x) = 3(-5) }$

Using the distributive property, we get:

${ 3y - 3x = -15 }$

Option C: Multiplying by 4

Now, let's multiply both sides of the equation by 4:

${ 4(y - x) = 4(-5) }$

Using the distributive property, we get:

${ 4y - 4x = -20 }$

Option D: Multiplying by 5

Finally, let's multiply both sides of the equation by 5:

${ 5(y - x) = 5(-5) }$

Using the distributive property, we get:

${ 5y - 5x = -25 }$

Conclusion

In conclusion, we have multiplied both sides of the equation by different constants and obtained four new equations. The correct option is not among the options A, B, C, or D. However, we can use these equations to solve the given system of equations.

Solving the System of Equations

We can use the method of substitution or elimination to solve the system of equations. Let's use the elimination method.

First, we can multiply the first equation by 1 and the second equation by 4 to make the coefficients of y's in both equations equal:

${ 4y + 3x = -6 }$

${ 4y - 4x = -20 }$

Subtracting the second equation from the first equation, we get:

${ 7x = 14 }$

Dividing both sides by 7, we get:

${ x = 2 }$

Substituting x = 2 into one of the original equations, we get:

${ y - 2 = -5 }$

Adding 2 to both sides, we get:

${ y = -3 }$

Therefore, the solution to the system of equations is x = 2 and y = -3.

Final Answer

The correct option is not among the options A, B, C, or D. However, we can use the equations obtained by multiplying both sides of the equation by different constants to solve the system of equations.

References

[1] "Linear Equations" by Math Open Reference
[2] "Solving Linear Equations" by Khan Academy

Q: What is the distributive property of multiplication over addition?

A: The distributive property of multiplication over addition states that for any real numbers a, b, and c:

${ a(b + c) = ab + ac }$

This property allows us to multiply a single value by the sum of two or more values.

Q: How do I multiply both sides of an equation by a constant?

A: To multiply both sides of an equation by a constant, you need to follow the distributive property of multiplication over addition. For example, if you want to multiply both sides of the equation y - x = -5 by 2, you would get:

${ 2(y - x) = 2(-5) }$

Using the distributive property, you would get:

${ 2y - 2x = -10 }$

Q: What is the difference between multiplying both sides of an equation by a constant and multiplying both sides of an equation by a variable?

A: Multiplying both sides of an equation by a constant involves multiplying each term in the equation by the same value. For example, if you multiply both sides of the equation y - x = -5 by 2, you would get:

${ 2y - 2x = -10 }$

On the other hand, multiplying both sides of an equation by a variable involves multiplying each term in the equation by the variable. For example, if you multiply both sides of the equation y - x = -5 by x, you would get:

${ xy - x^2 = -5x }$

Q: Can I multiply both sides of an equation by a fraction?

A: Yes, you can multiply both sides of an equation by a fraction. However, you need to be careful when multiplying by a fraction, as it can change the direction of the inequality. For example, if you multiply both sides of the equation y - x = -5 by 1/2, you would get:

${ \frac{1}{2}y - \frac{1}{2}x = -\frac{5}{2} }$

Q: How do I use the method of substitution to solve a system of equations?

A: To use the method of substitution to solve a system of equations, you need to solve one of the equations for one of the variables and then substitute that expression into the other equation. For example, if you have the system of equations:

${ y - x = -5 }$

${ 4y + 3x = -6 }$

You can solve the first equation for y and get:

${ y = x - 5 }$

Then, you can substitute this expression into the second equation and get:

${ 4(x - 5) + 3x = -6 }$

Simplifying this equation, you would get:

${ 7x = 14 }$

Dividing both sides by 7, you would get:

${ x = 2 }$

Substituting x = 2 into one of the original equations, you would get:

${ y = -3 }$

Therefore, the solution to the system of equations is x = 2 and y = -3.

Q: How do I use the method of elimination to solve a system of equations?

A: To use the method of elimination to solve a system of equations, you need to multiply both equations by necessary multiples such that the coefficients of one of the variables in both equations are the same. For example, if you have the system of equations:

${ y - x = -5 }$

${ 4y + 3x = -6 }$

You can multiply the first equation by 4 and the second equation by 1 to get:

${ 4y - 4x = -20 }$

${ 4y + 3x = -6 }$

Subtracting the first equation from the second equation, you would get:

${ 7x = 14 }$

Dividing both sides by 7, you would get:

${ x = 2 }$

Substituting x = 2 into one of the original equations, you would get:

${ y = -3 }$

Therefore, the solution to the system of equations is x = 2 and y = -3.

Q: What are some common mistakes to avoid when multiplying both sides of an equation by a constant?

A: Some common mistakes to avoid when multiplying both sides of an equation by a constant include:

Multiplying both sides of an equation by a variable instead of a constant.
Not following the distributive property of multiplication over addition.
Not checking if the equation is an identity or a contradiction before multiplying both sides by a constant.
Not simplifying the equation after multiplying both sides by a constant.

By avoiding these common mistakes, you can ensure that you are multiplying both sides of an equation by a constant correctly and obtaining the correct solution.