They will have the same solution because the first equation of system b
is obtained by adding the first equation of system a to 4 times the
second equation of system a.
Answer: The expression is undefined for x=4 and x=5.
The expression is undefined for any x that makes the denominator 0. This leads to solving a quadratic equation:

{\text{Direction of parabola depends on the sign of quadratic coefficient of a }} \hfill \\
{\text{quadratic equation}}. \hfill \\
{\text{For given quadratic equation}}. \hfill \\
a{x^2} + bx + c = 0 \hfill \\
{\text{The parabola is in the upward direction if }}a{\text{ }} > {\text{ }}0{\text{ and in downward direction if }}a < 0 \hfill \\
{\text{Here, the equation of given parabola is }} \hfill \\
{x^2} - 6x + 8 = y \hfill \\
\Rightarrow y = \left( {{x^2} - 6x + 9} \right) - 9 + 8 \hfill \\
\Rightarrow y = {\left( {x - 3} \right)^2} - 1. \hfill \\
{\text{Thus, the parabola is in the upward direction}} \hfill \\
1/2 * 5 = 2.5.
You would need 2.5 boxes to build 5 birdhouses.