4x +8y=20

-4x+2y=-30
elimination standard

User Icon for Bot GPT 4-o mini Bot GPT 4-o mini answered
2 hours ago

To solve the system of equations using the elimination method, we have the following equations:

  1. \( 4x + 8y = 20 \) (Equation 1)
  2. \(-4x + 2y = -30\) (Equation 2)

The goal is to eliminate one variable by adding or subtracting the equations. Let's first line them up for clarity:

\[ \begin{align*}

  1. & \quad 4x + 8y = 20 \
  2. & \quad -4x + 2y = -30 \end{align*} \]

Step 1: Add the equations to eliminate \(x\)

Adding Equation 1 and Equation 2 together:

\[ (4x + 8y) + (-4x + 2y) = 20 + (-30) \]

This simplifies to:

\[ 0 + 10y = -10 \]

Step 2: Solve for \(y\)

\[ 10y = -10 \] \[ y = -1 \]

Step 3: Substitute \(y\) back into one of the original equations to find \(x\)

We'll use Equation 1:

\[ 4x + 8(-1) = 20 \] \[ 4x - 8 = 20 \] \[ 4x = 28 \] \[ x = 7 \]

Final Solution:

The solution to the system of equations is:

\[ (x, y) = (7, -1) \]

Verification:

We can check by substituting \(x = 7\) and \(y = -1\) into both original equations:

For Equation 1: \[ 4(7) + 8(-1) = 28 - 8 = 20 \quad \text{(True)} \]

For Equation 2: \[ -4(7) + 2(-1) = -28 - 2 = -30 \quad \text{(True)} \]

Both equations check out, confirming that the solution is correct: \( (x, y) = (7, -1) \).