Chapter 4: Q. 4.18 (page 380)

Solve the system by elimination: $\{\begin{cases} 4 x + y = - 5 \\ - 2 x - 2 y = - 2 \end{cases}$

Short Answer

Expert verified

The solution of the system of equations is $(- 2, 3)$ .

Step by step solution

Step 1. Given Information.

We have been given the system of equations $\{\begin{cases} 4 x + y = - 5 \\ - 2 x - 2 y = - 2 \end{cases}$ .

Step 2. Eliminate y by multiplying a number in the first equation.

Multiply both sides of $4 x + y = - 5$ by 2.

$\{\begin{cases} 2 (4 x + y) = 2 (- 5) \\ - 2 x - 2 y = - 2 \end{cases}$

And,

localid="1644379547572"

\{\begin{cases} 8 x + 2 y = - 10 \\ - 2 x - 2 y = - 2 \end{cases}

Step 3. Add the equations resulting from Step 2 to eliminate one variable and solve it.

Add the $x' s, y' s$ and constants.

$\{\begin{cases} 8 x + 2 y = - 10 \\ - 2 x - 2 y = - 2 \end{cases}$

6 x = - 12

$x = - 2$

Step 4. Substitute the solution from Step 3 into one of the original equation and solve for the other variable.

Substitute $x = - 2$ into the first equation.

$4 x + y = - 5$

$4 (- 2) + y = - 5$

$- 8 + y = - 5$

$y = 3$

Step 5. Write the solution as an ordered pair.

Write it as $(x, y) .$

$(- 2, 3)$

Step 6. Check that the ordered pair is a solution to both original equations.

Substitute $x, y = - 2, 3$ into both original equations.

$4 x + y = - 5$

$4 (- 2) + 3 = - 5$

$- 8 + 3 = - 5$

$- 5 = - 5$

And,

$- 2 x - 2 y = - 2$

$- 2 (- 2) - 2 (3) = - 2$

$4 - 6 = - 2$

$- 2 = - 2$

Both equations are True.

The point localid="1644918289518" $(- 2, 3)$ is the solution to the system.

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Solve the system by elimination: $\{\begin{cases} 4 x + y = - 5 \\ - 2 x - 2 y = - 2 \end{cases}$

Short Answer

Step by step solution

Step 1. Given Information.

Step 2. Eliminate y by multiplying a number in the first equation.

Step 3. Add the equations resulting from Step 2 to eliminate one variable and solve it.

Step 4. Substitute the solution from Step 3 into one of the original equation and solve for the other variable.

Step 5. Write the solution as an ordered pair.

Step 6. Check that the ordered pair is a solution to both original equations.

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Solve the system by elimination:4x+y=-5-2x-2y=-2

Short Answer

Step by step solution

Step 1. Given Information.

Step 2. Eliminate y by multiplying a number in the first equation.

Step 3. Add the equations resulting from Step 2 to eliminate one variable and solve it.

Step 4. Substitute the solution from Step 3 into one of the original equation and solve for the other variable.

Step 5. Write the solution as an ordered pair.

Step 6. Check that the ordered pair is a solution to both original equations.

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Math Textbooks

Theoretical and Mathematical Physics

Applied Mathematics

Discrete Mathematics

Probability and Statistics

Calculus

Mechanics Maths

Study anywhere. Anytime. Across all devices.

Solve the system by elimination: $\{\begin{cases} 4 x + y = - 5 \\ - 2 x - 2 y = - 2 \end{cases}$