A principal is choosing between two field trips. The first cost $240 plus $40 per student. The second costs $600. For what number of students is the first trip more expensive than the second?

If there are 9 students attending then both field trips will cost the same. If there are more than 9 students attending then the second one cost cheaper.

Step-by-step explanation:

240 + 40x = 600

- 240           -240

40x = 360

40x/40 = 360/40

x = 9 students

if the eqn of the parabola is f(x) = (x-4)(x+2), we need to mult. this out to find the coordinates of the vertex.

then f(x) = x^2 + 2x - 4x - 8, and f(x) = x^2 - 2x - 8.

one way in which you can find the vertex is to calculate x = -b / (2a).   here, that comes to

        )

x = = 1.   f(1) = 1^2 - 2(1) - 8 = - 9.   vertex is at (1, -9).

        2(1) 

find another point on the curve:   let x=0, for which y=-8.   then (0, -8) is on the curve.   plot the vertex and this point and draw a smooth parabola thru both.

hope this