Graph the function f(x) = (x + 1)(x – 5). use the drop-down menus to complete the steps needed to graph the function. identify the x-intercepts: (–1, 0) and (5, 0) find the midpoint between the intercepts: (2, 0) find the vertex: find the y-intercept: plot another point, then draw the graph.

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

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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

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step-by-step explanation: