Solve the following system of equations. Show all work and solutions.

[tex]\[
\begin{array}{l}
y = 2x^2 + 6x + 4 \\
y = -4x^2 + 4
\end{array}
\][/tex]



Answer :

To solve the system of equations given by:

[tex]\[ \begin{array}{l} y = 2x^2 + 6x + 4 \\ y = -4x^2 + 4 \end{array} \][/tex]

we need to find the points [tex]\((x, y)\)[/tex] where both equations intersect. This can be done by setting the two equations equal to each other. Here’s the step-by-step procedure:

1. Set the equations equal to each other:

[tex]\[ 2x^2 + 6x + 4 = -4x^2 + 4 \][/tex]

2. Move all terms to one side to set the equation to zero:

[tex]\[ 2x^2 + 6x + 4 + 4x^2 - 4 = 0 \][/tex]

Combine like terms:

[tex]\[ 6x^2 + 6x = 0 \][/tex]

3. Factor the equation:

First, factor out the greatest common factor, which is [tex]\(6x\)[/tex]:

[tex]\[ 6x(x + 1) = 0 \][/tex]

4. Solve for [tex]\(x\)[/tex]:

Set each factor equal to zero:

[tex]\[ 6x = 0 \quad \text{or} \quad x + 1 = 0 \][/tex]

For [tex]\(6x = 0\)[/tex]:

[tex]\[ x = 0 \][/tex]

For [tex]\(x + 1 = 0\)[/tex]:

[tex]\[ x = -1 \][/tex]

5. Find the corresponding [tex]\(y\)[/tex]-values for each [tex]\(x\)[/tex]-value:

Substitute [tex]\(x = 0\)[/tex] into either original equation (we’ll use the first one):

[tex]\[ y = 2(0)^2 + 6(0) + 4 = 4 \][/tex]

So, the point [tex]\((0, 4)\)[/tex] is a solution.

Substitute [tex]\(x = -1\)[/tex] into either original equation (we’ll use the first one again):

[tex]\[ y = 2(-1)^2 + 6(-1) + 4 \][/tex]
[tex]\[ y = 2(1) - 6 + 4 \][/tex]
[tex]\[ y = 2 - 6 + 4 \][/tex]
[tex]\[ y = 0 \][/tex]

So, the point [tex]\((-1, 0)\)[/tex] is a solution.

Summary:

The solutions to the system of equations are the points where the two equations intersect, which are:

[tex]\[ (x, y) = (-1, 0) \quad \text{and} \quad (x, y) = (0, 4) \][/tex]