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Mathematics 21 Online
OpenStudy (anonymous):

Pre Calc Help

OpenStudy (anonymous):

OpenStudy (kaisertheslayer):

do want to know how or the answer??

OpenStudy (anonymous):

both please

OpenStudy (kaisertheslayer):

ok

OpenStudy (anonymous):

i know it is steepness but idk the exact rule

OpenStudy (anonymous):

can anyone help?

OpenStudy (kaisertheslayer):

yes but it would take a little

OpenStudy (anonymous):

thats fine

OpenStudy (anonymous):

I just need someone to explain how i know A based off looking at graph i know its negative but how do i know if its 1,2, etc

OpenStudy (kaisertheslayer):

alright, so f(x)=-(x-1)^2+4, does it make sense why

OpenStudy (anonymous):

can you give it in standard form

OpenStudy (anonymous):

ax^2 + bx + c

OpenStudy (anonymous):

and no im not sure how you got that

OpenStudy (kaisertheslayer):

okay so since we know the vertext, we know how much to shift it, up four and to the right 1, so thats how i got that

OpenStudy (kaisertheslayer):

to get the form you want, factor and simplfy it

OpenStudy (anonymous):

wait so if that was a steeper parabola what would you change

OpenStudy (kaisertheslayer):

the a and for the answer it is -1

OpenStudy (anonymous):

where is a in the formula you gave me?

Nnesha (nnesha):

alright you can find vertex point by looking at the graph right then substitute into this equation \[\huge\rm y = a(x-h)^2 +k\] vertex form of quadratic equation after that pick x and y values plug in solve for a :-)

OpenStudy (kaisertheslayer):

-x^2+2x+3

Nnesha (nnesha):

(x,y) (0,3)

OpenStudy (anonymous):

when y=0,x=-1 and 2

Nnesha (nnesha):

and by looking at the shape of graph u can easily find if a is negative or positive

OpenStudy (anonymous):

correction no,x=-1 and x=3

Nnesha (nnesha):

\(\color{blue}{\text{Originally Posted by}}\) @MathMan77 where is a in the formula you gave me? \(\color{blue}{\text{End of Quote}}\) \(\color{blue}{\text{Originally Posted by}}\) @KaiserTheSlayer alright, so f(x)=-(x-1)^2+4, does it make sense why \(\color{blue}{\text{End of Quote}}\) \[y=-(x-1)^2+4\] --- >\[\huge\rm y = -\color{red}{a}(x-h)^2 +k\] invisble one

OpenStudy (anonymous):

ah thank you!

Nnesha (nnesha):

\(\color{blue}{\text{Originally Posted by}}\) @Nnesha alright you can find vertex point by looking at the graph right then substitute into this equation \[\huge\rm y = a(x-h)^2 +k\] vertex form of quadratic equation after that pick x and y values plug in solve for a :-) \(\color{blue}{\text{End of Quote}}\) vertex point ( 1,4) (x,y) (0,3) \[\large\rm 3=a(0-1)^2 +4\] like this if u solve for a u will get the answer

OpenStudy (anonymous):

y=-(x+1)(x-3)=-(x^2-2x-3)=-(x^2-2x)+3=-(x^2-2x+1-1)+3=-(x^2-2x+1)+1+3 =-(x-1)^2+4

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