How do you graph quadratic functions?

if it's in the form of ax + bx +c , then to graph it you need to find the roots (intercept ) and its vertex and the y-intercept. to find the roots, you factor it, like this:

for example, you have this, x + 8x + 15, you factor to this: ( x + 3 ) ( x + 5).

those two numbers ( +3 and +5) , you switch the signs so that they are -3 and -5.

those are the roots. To find the y-intercept, in the expression, you make the x equal zero, and whatever number you simplify it to is the y-intercept. to find the vertex, you apply the formula x=-b/ 2a. whatever number you end up with is the x coordinate of the vertex. to find the y coordinate, you simply substitute the x value in the expression and simplify it and whatever you end up with is the y coordinate. you plot that coordinate, which is the vertex. it has to be curved. make it touch the y axis at the y intercept and the x axis at the roots. That's it.