Instructions: Solve the following system of equations algebraically. If there are no real solutions, type "none" in both blanks. If there is only one, type "none" in the other blank.

[tex]\[
\left\{\begin{array}{l}
y = \frac{1}{3}x - 3 \\
y = x^2 + 5x + 7
\end{array}\right.
\][/tex]

( , [tex]\(\square\)[/tex] ) ([tex]\(\square\)[/tex] , )



Answer :

Let's solve the following system of equations algebraically:
[tex]$ \left\{\begin{array}{l} y=\frac{1}{3} x-3 \\ y=x^2+5 x+7 \end{array}\right. $[/tex]

First, we set the right-hand sides of the two equations equal to each other since they both equal [tex]\( y \)[/tex]:

[tex]\[ \frac{1}{3} x - 3 = x^2 + 5x + 7 \][/tex]

Next, we'll bring all terms to one side to set the equation to 0:

[tex]\[ 0 = x^2 + 5x + 7 - \frac{1}{3} x + 3 \][/tex]

Combine like terms:

[tex]\[ 0 = x^2 + \left(5 - \frac{1}{3}\right)x + 10 \][/tex]

Simplify the coefficients:

[tex]\[ 0 = x^2 + \frac{15}{3}x - \frac{1}{3}x + 10 \\ 0 = x^2 + \frac{14}{3}x + 10 \][/tex]

Multiply through by 3 to clear the fractions:

[tex]\[ 0 = 3x^2 + 14x + 30 \][/tex]

Now, we solve the quadratic equation using the quadratic formula [tex]\( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \)[/tex]. Here, [tex]\( a = 3 \)[/tex], [tex]\( b = 14 \)[/tex], and [tex]\( c = 30 \)[/tex]:

[tex]\[ x = \frac{-14 \pm \sqrt{14^2 - 4 \cdot 3 \cdot 30}}{2 \cdot 3} \\ x = \frac{-14 \pm \sqrt{196 - 360}}{6} \\ x = \frac{-14 \pm \sqrt{-164}}{6} \\ x = \frac{-14 \pm \sqrt{164}i}{6} \][/tex]

Simplify the expression under the square root:

[tex]\[ x = \frac{-14 \pm 2\sqrt{41}i}{6} \\ x = \frac{-7 \pm \sqrt{41}i}{3} \][/tex]

Thus, we have two solutions for [tex]\( x \)[/tex]:
[tex]\[ x = \frac{-7}{3} - \frac{\sqrt{41}i}{3} \\ x = \frac{-7}{3} + \frac{\sqrt{41}i}{3} \][/tex]

Next, we find the corresponding [tex]\( y \)[/tex]-values by substituting each [tex]\( x \)[/tex] back into the first equation [tex]\( y = \frac{1}{3} x - 3 \)[/tex]:

For [tex]\( x = \frac{-7}{3} - \frac{\sqrt{41}i}{3} \)[/tex]:

[tex]\[ y = \frac{1}{3} \left(\frac{-7}{3} - \frac{\sqrt{41}i}{3}\right) - 3 \\ y = \frac{-7}{9} - \frac{\sqrt{41}i}{9} - 3 \\ y = - \frac{7}{9} - \frac{\sqrt{41}i}{9} - \frac{27}{9} \\ y = \frac{-34}{9} - \frac{\sqrt{41}i}{9} \][/tex]

And for [tex]\( x = \frac{-7}{3} + \frac{\sqrt{41}i}{3} \)[/tex]:

[tex]\[ y = \frac{1}{3} \left(\frac{-7}{3} + \frac{\sqrt{41}i}{3}\right) - 3 \\ y = \frac{-7}{9} + \frac{\sqrt{41}i}{9} - 3 \\ y = - \frac{7}{9} + \frac{\sqrt{41}i}{9} - \frac{27}{9} \\ y = \frac{-34}{9} + \frac{\sqrt{41}i}{9} \][/tex]

Therefore, the solutions to the system of equations are:
[tex]\[ \left(\frac{-7}{3} - \frac{\sqrt{41}i}{3}, \frac{-34}{9} - \frac{\sqrt{41}i}{9}\right) \text{ and }\left(\frac{-7}{3} + \frac{\sqrt{41}i}{3}, \frac{-34}{9} + \frac{\sqrt{41}i}{9}\right) \][/tex]

Since these solutions are complex, we do not have any real solutions for the given system of equations. Thus, the answers are:

[tex]\[ \text{(none, none) (none, none)} \][/tex]