Solve the system of equations.

7x+3y=−25

−7x+9y=−47

1 answer

To solve the system of equations:

  1. \( 7x + 3y = -25 \) (Equation 1)
  2. \( -7x + 9y = -47 \) (Equation 2)

We can use either the substitution method or the elimination method. Here, we'll use the elimination method.

First, we can add Equation 1 and Equation 2 together to eliminate \( x \):

\[ (7x + 3y) + (-7x + 9y) = -25 - 47 \]

This simplifies to:

\[ 0 + 12y = -72 \]

Now we can solve for \( y \):

\[ 12y = -72 \] \[ y = \frac{-72}{12} = -6 \]

Now that we have \( y \), we can substitute \( y = -6 \) back into Equation 1 to find \( x \):

\[ 7x + 3(-6) = -25 \] \[ 7x - 18 = -25 \] \[ 7x = -25 + 18 \] \[ 7x = -7 \] \[ x = \frac{-7}{7} = -1 \]

So, the solution to the system of equations is:

\[ x = -1, \quad y = -6 \]

Thus, the solution is \( (x, y) = (-1, -6) \).