Final answer:
The midpoint of the segment PQ is (4, 8), and the equation of the line of symmetry for the quadratic curve y=x² - 8x + 15 is x = 4.
Step-by-step explanation:
To calculate the coordinates of the midpoint of the straight line segment PQ, we use the midpoint formula which involves averaging the x-coordinates and the y-coordinates of the two points.
Since P has coordinates (1, 8) and Q has coordinates (7, 8),
the midpoint M will have coordinates ((1+7)/2, (8+8)/2) which is (4, 8).
The quadratic curve is given by y = x² - 8x + 15.
The equation of the line of symmetry for a parabola of the form y = ax² + bx + c is x = -b/(2a).
For this quadratic, a = 1 and b = -8,
so the line of symmetry is x = 8/(2*1),
which simplifies to x = 4.