Week 8- Graphing Quadratic Equations

In Week 8 of Pre- Calc, we finally learned how to graph a parabola and label the parabola using the general form (or parent form) y=ax^2+bx+c or the other formula which is y=a(x-p)^2+q . The first formula can go into the second formula to help you graph a parabola.

For the fomula y=a(x-p)^2+q :

y=ax^2 is the strench or compression of the parabola and it also indicates which way the parabola faces (up or down)

y=(x-number)^2 is where the parabola is on the y-axis (horizontal)

y=x^2+number is where the parabola is on the x-axis (vertical)

These portions of the formula are also called translation.

*Using the second fomula you can find the Vertex (the tip of the parabola) using (p,q). Note that the q is part of the vertex and not the y-intercept in the parent formula which is the c in y=ax^2+bx+c.

*You can also find out how much times the parabola touches the x-axis by using the discriminat (if its a positive number then it touches 2 times, if its a 0 then once and if its a negative number the 0 times)

We can find the vertex, axis of symmetry and the translation by looking at the parabola and applying it in y=a(x-p)^2+q

Vertex= (5,4)

Axis of Symmetry is x=5 (axis of symmetry is the line that goes straight through the parabola and makes it mirror each side)

The stretch of the parabola is y=3x^2 because if you follow the basic 1,3,5,7 and multiply by 3 which would be 3,9,15,21 and you can see on the graph that it goes up by 3 first then 9 and so on. We also know that it a positive because it is facing up.

The parabola also moves 5 units to the right so it would be y=(x-5)^2

*If it is adding then the parabalo moves to the left, if it is subtracting then in moves to the right. (opposite)

The parabola also moves 4 units up so it would be y= x^2+4

Now we can apply what we know in the formula y=a(x-p)^2+q which would be 3(x-5)^2+4

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