i would also like to know how you did it
what's the vertex form of the parabola ?
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)
so like (y-2)=a(x--4)^2
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
so a =-2
i appreciate your help btw
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
x= 0,-8 Correct?
hmm plz show a little work...
im using an online calculator because the only calculator we have broke im not quite shure how to do the steps myself without it.
hmm well do you want to know how to work it out without calculator ?
couldent hurt mind if i get my notepad and pencil
ok i got it
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)
|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
or dise tge 4 not have an x
yes right |dw:1443017933992:dw| and then 4(x+4) = 4x +16 now combine like terms
x^2 +4x is correct :=)
ohh ok Thanks!
|dw:1443018028522:dw|alright now combine like terms
do you know what are `like terms ` ?
i beilive they are x2 and 16 4x and 4x
hmm like terms that contains same variables
x^2 is same as 1x^2 so 16 and 1x^2 are the same ?
there is a variable with 1 but no variable with 16
hmm so what dose that mean?
hmm like terms that contains the same variable so 1x^2 and 16 are like terms or not ?
yes right so just combine 4x+4x just add the coefficient here is an example 2x+4x=(2+4)x =6x
well 4x+4x is 8x
yes right \[-32=-2(x^2+8x+16)\] now distribute parentheses by -2
umm ... i got 0,-8
same as my answer from before so is it correct?
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
sorry iys touch im bad at numbers
Sorry my its just im bad at numbers*
so the asnwer to my origanal problem is 0,-8
err 0,-8 was inccorect on my question
are the solution you should write in two order pair (x1,y1)(x2,y2)
remember x-intercept when y =0 so when x=0 y=0 for 2nd order pair when x=-8 y=0