Use the elimination method to solve the linear-quadratic system: y = x^2 + 10, y = -7x - 2

1 answer

To solve the system of equations using the elimination method, we'll set the two equations equal to each other since both are equal to \( y \).

The two equations are:

  1. \( y = x^2 + 10 \)
  2. \( y = -7x - 2 \)

Setting them equal to each other gives:

\[ x^2 + 10 = -7x - 2 \]

To solve for \( x \), we can rearrange the equation by moving all terms to one side:

\[ x^2 + 7x + 10 + 2 = 0 \]

This simplifies to:

\[ x^2 + 7x + 12 = 0 \]

Next, we will factor the quadratic equation:

\[ (x + 3)(x + 4) = 0 \]

Setting each factor to zero gives us the solutions for \( x \):

  1. \( x + 3 = 0 \) → \( x = -3 \)
  2. \( x + 4 = 0 \) → \( x = -4 \)

Now that we have the \( x \)-values, we can substitute these back into either original equation to find the corresponding \( y \)-values. We'll use the second equation, \( y = -7x - 2 \).

For \( x = -3 \):

\[ y = -7(-3) - 2 = 21 - 2 = 19 \]

The first solution is \( (-3, 19) \).

For \( x = -4 \):

\[ y = -7(-4) - 2 = 28 - 2 = 26 \]

The second solution is \( (-4, 26) \).

Putting it all together, the solutions to the system of equations are:

\[ \boxed{(-3, 19)} \quad \text{and} \quad \boxed{(-4, 26)} \]