What are the solutions of the following system?

[tex]\[
\left\{\begin{array}{r}
x^2 + y^2 = 25 \\
2x + y = -5
\end{array}\right.
\][/tex]

A. [tex]\((0, -5)\)[/tex] and [tex]\((-5, 5)\)[/tex]

B. [tex]\((0, -5)\)[/tex] and [tex]\((5, -15)\)[/tex]

C. [tex]\((0, -5)\)[/tex] and [tex]\((-4, 3)\)[/tex]

D. [tex]\((0, -5)\)[/tex] and [tex]\((4, -13)\)[/tex]



Answer :

To solve the given system of equations, we have:

[tex]\[ \left\{ \begin{array}{r} x^2 + y^2 = 25 \\ 2x + y = -5 \end{array} \right. \][/tex]

Let's solve it step-by-step:

1. First Equation: [tex]\(x^2 + y^2 = 25\)[/tex]

2. Second Equation: [tex]\(2x + y = -5\)[/tex]

We will solve the second equation for [tex]\(y\)[/tex]:
[tex]\[ y = -5 - 2x \][/tex]

Now substitute this expression for [tex]\(y\)[/tex] into the first equation:
[tex]\[ x^2 + (-5 - 2x)^2 = 25 \][/tex]

Simplify the equation:
[tex]\[ x^2 + (25 + 20x + 4x^2) = 25 \][/tex]
[tex]\[ x^2 + 4x^2 + 20x + 25 = 25 \][/tex]
[tex]\[ 5x^2 + 20x + 25 = 25 \][/tex]

Subtract 25 from both sides:
[tex]\[ 5x^2 + 20x = 0 \][/tex]

Factor out the common factor:
[tex]\[ 5x(x + 4) = 0 \][/tex]

This gives us two solutions for [tex]\(x\)[/tex]:
[tex]\[ x = 0 \quad \text{or} \quad x = -4 \][/tex]

Now we will find the corresponding [tex]\(y\)[/tex] values for each [tex]\(x\)[/tex]:

- For [tex]\(x = 0\)[/tex]:
[tex]\[ y = -5 - 2(0) = -5 \][/tex]
So one solution is [tex]\((0, -5)\)[/tex].

- For [tex]\(x = -4\)[/tex]:
[tex]\[ y = -5 - 2(-4) = -5 + 8 = 3 \][/tex]
So the other solution is [tex]\((-4, 3)\)[/tex].

Therefore, the solutions to the system of equations are [tex]\((0, -5)\)[/tex] and [tex]\((-4, 3)\)[/tex].

Among the given options, the correct one is:

[tex]\[ (0, -5) \text{ and } (-4, 3) \][/tex]