Find the x-intercepts of the parabola with vertex (-4,2)and y Intercept (0,-30) Wright answer if this form (x1,y1)(x2,y2).

- anonymous

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- schrodinger

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- anonymous

i would also like to know how you did it

- Nnesha

what's the vertex form of the parabola ?

- anonymous

(y-k)=a(x-h)^2

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## More answers

- anonymous

Bruh...
okay here: http://openstudy.com/study#/updates/4fe123c7e4b06e92b8705343

- Nnesha

hmm add k both sides so it would be \[\huge\rm y=a(x-h)^2+k\] vertex form
where (h,k) is the vertex
so substitute (h,k) for ( -4,2)

- anonymous

so like (y-2)=a(x--4)^2

- Nnesha

ye that would work
so y-intercept is (0,-30) where x =0 and y =-30 so plugin \[\huge\rm -30-2=a(0-(-4))^2\] now solve for a

- anonymous

so a =-2

- anonymous

i appreciate your help btw

- Nnesha

yes right now u can find x-intercept \[\huge \rm -30-2=-2(x-(-4))^2\]
solve for x
let me know if you don't know how to work it out

- anonymous

x= 0,-8 Correct?

- Nnesha

hmm plz show a little work...

- anonymous

im using an online calculator because the only calculator we have broke im not quite shure how to do the steps myself without it.

- Nnesha

hmm well do you want to know how to work it out without calculator ?

- anonymous

couldent hurt mind if i get my notepad and pencil

- anonymous

ok i got it

- Nnesha

alright first we can multiply negative by (-4)
-1 times -4 = 4 ( negative times negative = positive )
\[\huge \rm -30-2=-2(x+4))^2\]
-30-2 = -32
\[\huge \rm -32=-2(x+4)^2\]
now we should foil (x+4)^2
`(x+4)^2 `is same as (x+4)(x+4)

- Nnesha

|dw:1443017713689:dw|
now we should distribute 2nd parentheses by first and 2nd term of the 2nd parentheses (foil method )
so multiply left first term by top

- Nnesha

x(x+4) =??

- anonymous

x^2+4x ?

- anonymous

or dise tge 4 not have an x

- Nnesha

yes right |dw:1443017933992:dw|
and then 4(x+4) = 4x +16 now combine like terms

- Nnesha

x^2 +4x is correct :=)

- anonymous

ohh ok Thanks!

- Nnesha

|dw:1443018028522:dw|alright now combine like terms

- Nnesha

do you know what are `like terms ` ?

- anonymous

no :C

- anonymous

i beilive they are x2 and 16 4x and 4x

- Nnesha

hmm
like terms that contains same variables

- Nnesha

x^2 is same as 1x^2 so
16 and 1x^2 are the same ?

- Nnesha

there is a variable with 1 but no variable with 16

- anonymous

hmm so what dose that mean?

- Nnesha

hmm
like terms that contains the same variable
so 1x^2 and 16 are like terms or not ?

- anonymous

no coreect?

- Nnesha

yes right so just combine 4x+4x just add the coefficient
here is an example
2x+4x=(2+4)x =6x

- anonymous

well 4x+4x is 8x

- Nnesha

yes right \[-32=-2(x^2+8x+16)\] now distribute parentheses by -2

- Nnesha

|dw:1443018609249:dw|

- anonymous

umm ... i got 0,-8

- anonymous

same as my answer from before so is it correct?

- Nnesha

ohh well i was just asking abt -2(x^2+8x+16) but yes that is the answer if u use calculator not gonna force u to work by hand :D

- anonymous

sorry iys touch im bad at numbers

- anonymous

Sorry my its just im bad at numbers*

- anonymous

so the asnwer to my origanal problem is 0,-8

- anonymous

thanks

- Nnesha

yw

- anonymous

err 0,-8 was inccorect on my question

- anonymous

yeet

- Nnesha

are the solution you should write in two order pair (x1,y1)(x2,y2)

- Nnesha

remember x-intercept when y =0
so when x=0 y=0
for 2nd order pair when x=-8 y=0

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