Solve the system of equations below using substitution. You must show all work to earn full credit.



y=2x+3


3x−y=−5

1 answer

To solve the system of equations using substitution, we have the following two equations:

  1. \( y = 2x + 3 \) (Equation 1)
  2. \( 3x - y = -5 \) (Equation 2)

Step 1: Substitute Equation 1 into Equation 2

Since we have \( y \) expressed in terms of \( x \) from Equation 1, we can substitute \( y \) in Equation 2.

Substituting \( y \) in Equation 2 gives us:

\[ 3x - (2x + 3) = -5 \]

Step 2: Simplify the equation

Now, simplify the equation:

\[ 3x - 2x - 3 = -5 \]

This simplifies to:

\[ x - 3 = -5 \]

Step 3: Solve for \( x \)

Next, we add 3 to both sides of the equation to isolate \( x \):

\[ x = -5 + 3 \] \[ x = -2 \]

Step 4: Substitute \( x \) back into Equation 1 to find \( y \)

Now that we have \( x \), we can substitute \( x = -2 \) back into Equation 1 to find \( y \):

\[ y = 2(-2) + 3 \] \[ y = -4 + 3 \] \[ y = -1 \]

Step 5: Write the solution

The solution to the system of equations is:

\[ (x, y) = (-2, -1) \]

Step 6: Verify the solution

Finally, we can verify the solution by substituting \( x = -2 \) and \( y = -1 \) back into the original equations to ensure they hold true.

  1. For Equation 1: \[ y = 2x + 3 \Rightarrow -1 = 2(-2) + 3 \Rightarrow -1 = -4 + 3 \Rightarrow -1 = -1 \quad \text{(True)} \]

  2. For Equation 2: \[ 3x - y = -5 \Rightarrow 3(-2) - (-1) = -5 \Rightarrow -6 + 1 = -5 \Rightarrow -5 = -5 \quad \text{(True)} \]

Both equations verify correctly, confirming that the solution \((-2, -1)\) is indeed correct.

Thus, the final answer is:

\[ (x, y) = (-2, -1) \]