Solving by using elimination (algebra 1)

4x + 8y = 20
-4x + 2y = -30

1 answer

To solve the system of equations using the elimination method, we start with the two equations:

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

The goal of the elimination method is to eliminate one of the variables by adding or subtracting the equations.

Let's add Equation 1 and Equation 2:

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

Simplifying both sides:

\[ 4x - 4x + 8y + 2y = 20 - 30 \] \[ 0 + 10y = -10 \]

Now, we can solve for \(y\):

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

Next, we'll substitute \(y = -1\) back into one of the original equations to find the value of \(x\). We'll use Equation 1:

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

Now we have the solution:

\[ x = 7, \quad y = -1 \]

Thus, the solution to the system of equations is \( (x, y) = (7, -1) \).

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