14x−4y=40

7x + 8 y= -10
solve by elimanation

1 answer

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

  1. \( 14x - 4y = 40 \) (Equation 1)
  2. \( 7x + 8y = -10 \) (Equation 2)

Step 1: Make the coefficients of \(y\) in both equations equal.

We can multiply Equation 1 by 2 to get the coefficients of \(y\) to match:

\[ 2(14x - 4y) = 2(40) \]

This gives us:

\[ 28x - 8y = 80 \quad \text{(Equation 3)} \]

Now we have:

  1. \( 28x - 8y = 80 \) (Equation 3)
  2. \( 7x + 8y = -10 \) (Equation 2)

Step 2: Add Equation 3 and Equation 2.

We will add the two equations together to eliminate \(y\):

\[ (28x - 8y) + (7x + 8y) = 80 - 10 \]

This simplifies to:

\[ 35x + 0y = 70 \]

So we have:

\[ 35x = 70 \]

Step 3: Solve for \(x\).

Divide both sides by 35:

\[ x = \frac{70}{35} = 2 \]

Step 4: Substitute \(x = 2\) back into one of the original equations.

Let's use Equation 2:

\[ 7x + 8y = -10 \]

Substituting for \(x\):

\[ 7(2) + 8y = -10 \]

This simplifies to:

\[ 14 + 8y = -10 \]

Subtract 14 from both sides:

\[ 8y = -10 - 14 \] \[ 8y = -24 \]

Now, divide by 8:

\[ y = \frac{-24}{8} = -3 \]

Final Solution:

The solution for the system of equations is:

\[ x = 2, \quad y = -3 \]

Thus, the point of intersection is \( (2, -3) \).