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Mathematics 13 Online
OpenStudy (anonymous):

I can't figure this one out.. MEDAL AND FAN FOR ANYONE WHO CAN UN-CONFUZZLE ME!! For the function f(x) = –(x + 1)2 + 4, identify the vertex, domain, and range.

OpenStudy (loser66):

Where are you stuck?

OpenStudy (anonymous):

mostly the vertex

OpenStudy (loser66):

open parentheses, what do you have for f(x) ?

OpenStudy (anonymous):

f(x)=-x+1^2+4

OpenStudy (loser66):

nnnnnnnnnnnnnope

OpenStudy (loser66):

\(f(x) = -(x+1)^2 +4\) redo, please. Use Foil

OpenStudy (anonymous):

-x+5? after you simplify ?

OpenStudy (anonymous):

How do you find out the range aswell I vaguely remember

OpenStudy (loser66):

\((x+1)^2 =(x+1)(x+1)\) ,using Foil to open parentheses

OpenStudy (anonymous):

Oh ya I forgot you had to do that with squared binomials

OpenStudy (anonymous):

X^2+2x+1

OpenStudy (loser66):

Yup, don't forget, before them, you have - sign, after them you have +4 now, put all in, what do you get for f(x) ??

OpenStudy (anonymous):

Where did you get the +4 from?

OpenStudy (loser66):

From the original problem.

OpenStudy (anonymous):

Oh ok, did I mess up the foil? You said something about a negative and when I plugged 4 into \[x ^{2}+2x+1 \] I got 25 and that's not one of the choices for the y-coordinate and it doesn't really make sense

OpenStudy (loser66):

NOOOOOOOOOPe

OpenStudy (loser66):

\(f(x) = \huge \color{red}{-} (x+1)^2 +4\\~~~~~~~~~~=\huge\color{red}{-} (x^2+2x+1)+4\\=\huge -x^2-2x-1+4\) ok??

OpenStudy (loser66):

hey!!! YES or NO?

OpenStudy (anonymous):

OOHHH

OpenStudy (anonymous):

YES got it :) but how bought the range? Ik the domains gunna be all real numbers

OpenStudy (loser66):

wait, simplify it, please.

OpenStudy (loser66):

don't know??? why?? -1+4 =?

OpenStudy (anonymous):

3?

OpenStudy (loser66):

yes, so that \(f(x) =-x^2-2x+3\) right?

OpenStudy (loser66):

From this, the REAL process starts.

OpenStudy (loser66):

what are a, b, c on it?

OpenStudy (loser66):

a=? b=? c=?

OpenStudy (anonymous):

a=-1 b=-2 c=3

OpenStudy (loser66):

yup, hence the vertex has x-coordinate is \(x= -b/2a\) , hence x =??

OpenStudy (anonymous):

x=4

OpenStudy (loser66):

\(x=-\dfrac{b}{2a}=-\dfrac{-2}{2*(-1)}=??\)

OpenStudy (anonymous):

1

OpenStudy (anonymous):

so the vertex is 1,4?

OpenStudy (anonymous):

TY FOR HELPING ME FIGURE HAT PART OUT :)))) but how do I know what the range is going to be?

OpenStudy (loser66):

to it, when you have vertex, and the parabola is downward, hence the range is from - infinitive to y-coordinate of the vertex.

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