Allgemeine Form in Scheitelpunktform umwandeln?

Kann mir einer Schritt für Schritt erklären, wie man es umwandelt . Wenn ich im Internet danach suche, kriege nur Beispiele, wo vor dem x eine zahl steht, die ich ausklammern kann und halbieren muss. Ich weiß nicht, wie ich x halbieren soll oder x^2 ausklammern kann

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Willy1729
10 months ago

Hello,

the general form of a parabola is ax2+bx+c.

The vertex is where the derivation is equal to zero.

Discharge is generally f'(x)=2ax+b.

2ax+b=0; 2ax=-b; x=-b/(2a).

For x=-b/(2a), therefore, the vertex of a parabola lies.

You get the y coordinate of the vertex when you use -b/(2a) instead of x in f(x):

f(-b/(2a))=a*(-b/(2a))2+b*(-b/(2a)))+c.

This can be summarized to a*b2/4a2)-b2/(2a)+c and further to
b2/(4a)-b2/(2a)+c.

Extend -b2/(2a) with 2, you can combine it with b2/(4a) to -b2/(4a).

If you expand c with 4a, you can put everything on a break:

(4ac-b2)/(4a).

This is the y coordinate of the vertex of an x-popular parabola.

The vertex is therefore S (-b/(2a)|(4ac-b2)/(4a).

Now you can convert the general form over the square supplement.

First you draw the factor a from ax2+bx+c:

a*(x2+(b/a)x+c/a).

Now you convert the first two summands in the clamp by the square addition (b/(2a))2=b2/(4a2) to x2+(b/a)x+b2/(4a2)=(x+b/(2a)2)2.

Of course, you have to withdraw the supplement b2/(4a2).

This results in a*((x+b/(2a))2-b2/(4a2)+c/a).

After extension, the a*((x+b/(2a))2+(4ac-b2)/(4a2) results.

Take everything except the binomist out of the clamp:

a*(x+b/(2a))2+(4ac-b2)/(4a).

Compare this with the coordinates of the vertex:

(4ac-b2)/(4a) is the y coordinate of the vertex. You can replace this term with the letter e by defining e=(4ac-b2)/(4a).

If you set the x coordinate of the apex -b/(2a) equal to d, then b/(2a) is the same as -d.

So you come to the vertex form f(x)=a*(x-d)2+e with vertex S (d|e).

Best regards,

Willy

Willy1729
10 months ago
Reply to  Mathefragen139

Then you’re missing a lot of basics. My answer relates to the conversion of the general form of a parabola into the vertex form.

Willy1729
10 months ago
Reply to  Mathefragen139

Set the specific values of the given function for a, b and c.

If the equation sounds for example f(x)=3×2-x+4, then a=3, b=-1 and c=4.

Put in, ready.

If the x coordinate of the apex is -b/(2a) and a is equal to 3 and b=-1, then the apex is at x=1/(2*3)=1/6.

Now you can either use and calculate the values of a, b and c in the term for the y coordinate or simply insert x=-1/6 into the function equation, which then comes out to the same.

With Sy (y coordinate of the vertex) equal to (4ac-b2)/(4a) and a=3, b=-1, c=4, you come to coordinate 47/12, namely (4*3*4-1)/12. If you insert x=1/6 in f(x)=3×2-x+4 directly, you will get as a y coordinate of the vertex
3*(1/6)2-1/6+4=47/12, that is exactly the previous result.

Willy1729
10 months ago

In my answer, it was above all about showing how to get to the vertex form of a parabola f(x)=a*(x-d)2+e. Where do the d and the e come from and why is it the same as f(x)=ax2+bx+c?

evtldocha
10 months ago

You make a square addition (Note: – x = – 1·x) as usual

Sketch:

Halbrecht
10 months ago

only get examples where there’s a number in front of the x that I can clip and halve.

simple : There is a not written +1 or -1 ahead

thus halved +0.5 or -0.5

Halbrecht
10 months ago
Reply to  Mathefragen139

no: you write 2x for two_x or only x for one_x (1x)

also with x2 = 1×2 or -x2 = -1×2 the 1 is not pushed

.

In the pq formula, at x2 +x+7 the p=+1 and the q=+7

Hamburger02
10 months ago

The parabel has a horizontal tangent at the vertex:

p(x) = x^2 – x + 2

p'(x) = 2x – 1 = 0
2x = 1
x = 1/2

p(0.5) = 0.25 – 0.5 + 2 = 1.75

Solution: S(0.5/1,75)

milan558
10 months ago

you can enter this, you will see the individual steps:

https://www.mathepower.com/scheitelpunktform.php

if you ask yourself how to come to a half you have to share the prefactor of x by 2 (if I have that right in memory)

milan558
10 months ago
Reply to  Mathefragen139

there is actually 1*x

milan558
10 months ago

there is 1*x^2-1*x+2, if there is no number in front of x this is one 1 you have a x if you had two there would be 2*x