Converting Quadratic Equations to Standard Form

In summary, completing the square and factoring can help you rewrite an equation in standard form, which is useful for solving and graphing parabolas. In this specific conversation, the equation y = x^2 + 8x + 20 was already in standard form, but by completing the square, we can see that it can also be factored as (x + 4)^2 + 4.
  • #1
quickclick330
83
0
Change the equation to standard form.

y = x^2 + 8x + 20


I thought this was the standard form for parabolas?? I tried this as the answer but it said it was wrong

y = (x+4)^2 +4

Thanks for the help! :-)
 
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  • #2
Complete the Square to the general form of the equation (and then undo this) and you will have something which is factorable. For your exercise, you want to add and subtract (8/2)^2 , and I will leave the rest of this for your effort to continue.
 
  • #3
okay so completing the square gives me

y = x^2 +8x + 20 + 16 - 16
y = (x^2 + 8x +16) + 4
then factor...

y = (x + 4)^2 + 4

which is exactly what I got before?
 
  • #4
quickclick330 said:
okay so completing the square gives me

y = x^2 +8x + 20 + 16 - 16
y = (x^2 + 8x +16) + 4
then factor...

y = (x + 4)^2 + 4

which is exactly what I got before?

That appears to be correct. That IS the standard form for your equation given in your exercise. The parabola has been shifted upward by 4 units and to the left by 4 units from standard position.
 
  • #5
okay thanks...I'll ask the teacher then, its an online submission homework so maybe somethings wrong. hopefully.
 

What is the standard form of a parabola?

The standard form of a parabola is y = ax^2 + bx + c, where a, b, and c are constants and a is not equal to 0. This form is also known as the quadratic form.

What does each term in the standard form represent?

The term a represents the coefficient of the squared term, b represents the coefficient of the linear term, and c represents the constant term. These values determine the shape, direction, and position of the parabola.

What is the difference between a positive and negative value of a in the standard form?

If a is positive, the parabola opens upwards and has a minimum point. If a is negative, the parabola opens downwards and has a maximum point. The value of a also affects the steepness of the curve.

Can the standard form be used to graph any parabola?

Yes, the standard form can be used to graph any parabola. By substituting different values for a, b, and c, you can create different parabolas with varying shapes and positions.

How can the standard form be rewritten to find the vertex of a parabola?

The standard form can be rewritten as y = a(x - h)^2 + k, where h and k represent the coordinates of the vertex. This form is known as the vertex form and can be used to easily find the vertex of a parabola.

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