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Solve the systems of equations in Exercises \(8-11\) by elimination, and check your solutions. Give the following information: \(\cdot\) which variable you eliminated \(\cdot\) whether you added or subtracted equations \(\bullet\) the solution $$ \begin{array}{l}{3 p+2 q=13} \\ {3 p-2 q=-5}\end{array} $$

Short Answer

Expert verified
Eliminate \ by adding equations. Solution: \[ p = \frac{4}{3} \], \[ q = 4.5 \]

Step by step solution

01

Write down the given system

The system of equations to solve is: \(3p + 2q = 13\) \(3p - 2q = -5\)
02

Choose the variable to eliminate

Choose to eliminate the variable \ by noticing that the coefficients of \ in the two equations are opposites: \(3p + 2q\) and \(3p - 2q\).
03

Add the equations

Add the two equations to eliminate \: \( (3p + 2q) + (3p - 2q) = 13 + (-5) \)
04

Simplify the equation

\[ 3p + 3p + 2q - 2q = 13 - 5 \] This simplifies to: \[ 6p = 8 \] Divide by 6 to solve for \[ p \]: \[ p = \frac{8}{6} = \frac{4}{3} \]
05

Substitute back to find the other variable

Use the value of p to find q. Substitute \ in one of the original equations, e.g., \: \[ 3(\frac{4}{3}) + 2q = 13 \] This simplifies to: \[ 4 + 2q = 13 \] Subtract 4 from both sides: \[ 2q = 9 \] Divide by 2 to solve for \[ q \]: \[ q = \frac{9}{2} = 4.5 \]
06

Check the solution

Substitute \ and \ into the other original equation \( 3p - 2q = -5 \) and verify: \[ 3(\frac{4}{3}) - 2(4.5) = -5 \] Simplifies to: \[ 4 - 9 = -5 \] \[ -5 = -5 \] Since both addition and subtraction work, the solution is verified.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

elimination method
The elimination method is a great technique for solving systems of linear equations. It works by adding or subtracting equations to eliminate one of the variables, making it easier to solve for the remaining variable. Let's break down how this works using an example equation.
In our exercise, the goal was to eliminate one of the variables, either \(p\) or \(q\). Notice that the coefficients of \(q\) are opposites in the two equations: \(2q\) in the first and \(-2q\) in the second.
This tells us that adding the two equations will cancel out \(q\), leaving us with only \(p\) to solve for. The steps can be quick and simple with practice.
Here, the variable \(q\) was successfully eliminated by adding the equations together.
solving equations
Solving equations is a fundamental skill in algebra. It involves finding the values of the variables that make the equation true.
When solving the simplified equation \(6p = 8\), we divided both sides by 6 to isolate \(p\). This resulted in \(p = \frac{4}{3}\).
Next, we substituted the value of \(p\) back into one of the original equations to find \(q\). This two-step approach is typical in problems like these.
We confirmed our solution by checking both \(p\) and \(q\) in the original equations. Verifying solutions ensures we solved correctly.
substitution method
The substitution method is another efficient way to solve systems of equations. This method involves solving one of the equations for one variable and then substituting that expression into the other equation.
While it wasn’t the primary method used in our example, understanding it is beneficial. If we had solved for \(p\) or \(q\) first, we could then make a substitution into the other equation.
For instance, solving \(3p + 2q = 13\) for \(p\) gives \(p = \frac{13-2q}{3}\).
Substituting this into the second equation would yield \(3 \times \frac{13-2q}{3} - 2q = -5\), which can then be solved for \(q\).
This method can often be helpful when the coefficients are not easily eliminated by addition or subtraction.
algebraic manipulation
Algebraic manipulation is the process of rearranging and simplifying equations using various algebraic rules. It forms the core of solving equations.
In our problem, algebraic manipulation allowed us to isolate variables and simplify equations. We performed operations like addition, subtraction, and division.
When we added the two equations, we combined like terms to eliminate \(q\). We then simplified the resulting equation to solve for \(p\).
These steps, while straightforward in this example, showcase critical techniques used in algebra to tackle more complex problems.
Remember, being comfortable with algebraic manipulation can make solving systems of equations much easier and faster.

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Most popular questions from this chapter

Megan is writing a computer game in which a player stands on the balcony of a haunted house and drops water balloons on ghosts below. The player chooses where the balloon will land and then launches it. Since water splatters, Megan’s game gives the player points if a ghost is anywhere within a square centered where the balloon lands. The square extends 15 units beyond the center in all four directions. That is, if both of the ghost’s coordinates are 15 units or less from the center, the player has scored a hit. Suppose the balloon lands at \((372,425) .\) The nearest ghost has the coordinates \((x, y),\) and it counts as a hit by the game. Use inequalities to describe the possible values for \(x\) and \(y .\) (Hint: You will need two inequalities, one for \(x\) and one for \(y .\) Should you say "and" or "or' between them?)

A cartoon cat pushes a piano out of a fourth-story window that is approximately 50 feet above the sidewalk a. An object falls a distance of \(s=16 t^{2}\) feet in \(t\) seconds. For how long will the piano fall before it hits the sidewalk? b. Suppose the cat intended to smash his nemesis, the mouse, on the sidewalk below. But the mouse pulls a trampoline out of his pocket and the piano bounces back toward the cat at an initial velocity of 100 feet per second. The height \(h\) of the piano \(t\) seconds after it hits the trampoline can be found using the piano \(h=100 t-16 t^{2} .\) Graph this equation, and use your graph to estimate how long it takes the piano to return to the fourth-story window.

Solve the systems of equations in Exercises \(8-11\) by elimination, and check your solutions. Give the following information: \(\cdot\) which variable you eliminated \(\cdot\) whether you added or subtracted equations \(\bullet\) the solution $$ \begin{array}{l}{9 s+2 t=3} \\ {4 s+2 t=8}\end{array} $$

Rewrite each expression as simply as you can. $$\left(-m^{2} n\right)^{4}$$

Economics For a school concert, a small printing business charges \(\$ 8\) for printing 120 tickets and \(\$ 17\) for printing 300 tickets. Both of these total costs include a fixed cost and a unit cost per ticket. That is, the cost for \(n\) tickets is \(c=A+B n,\) where \(A\) is the business's fixed charge per order and \(B\) is the charge per ticket. a. Using the fact that it costs \(\$ 8\) to have 120 tickets printed, write an equation in which \(A\) and \(B\) are the only unknown quantities. b. Write a second equation using the cost of \(\$ 17\) for 300 tickets. c. Use the substitution method to find the business's fixed and variable charges.

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