Question

Sketch a graph of the equation
y=-x^2 + x + 10 for x=0...x=4

i think that the equation y=-x2+x+10 is a parabola and for the x values that were given am i suppose to plug in?

Answer 1

Yes it is a curve that starts in the top left quarter (x-ve , y+ve) drops to a minimum at x=-0.5, and then climbs into top right quarter (x=ve, y+ve), but does not cross the x axis. You are expected to plot the two points on the line.

You can tell that it does not cross the x axis when (if the equation is in the form)

y=ax^2+bx+c

b^2<=4ac

and here

1^2<4.1.10

so does not cross the x axis.