dum dum (1 Viewer)

[fashionista]

k this is a reely stupid question bu im gunna ask anyways.
for a graphing question like this
y=sq.rt {[(x^2)-9]^2}
wud it b possible to cancel out the square root and the ^2??? bcoa if u do then u jus get a normal quadratic but im not quite gettin y this graph is jus the quadratic ((x^2)-9) with the bit below the y-axis reflected above the x-axis.....becayse i tried graphing ((x^2)-9)^2 and thats like a quartic curve..maybe its jus me or maybe its jus...........me
anyways can sum 1 please clarify this matter for me? i noe its a dum question but i had to ask.
thanking u in advancings

 

[kimmeh]

well you know that its always going to be positive.. because of the x^2 and that the funstion is a square root..
though i dont think you can remove it.. i've left 4u maths for too long.. maybe this is a sign i should go revise

 

[Lainee]

No, you cannot simply cancel the square root and the square. When you remove them you get y=|(x^2)-9| (where the bars are absolute values in case it wasn't clear )
So that's why it's just the quadratic drawn with the negative parts flipped up.

 

[fashionista]

lol..i kinda understand wut i was talkin bout before..thing is ((x^2)-9) is a quartic that isn't all cuspy on the x-axis, but...no no..i understand that bit now tis all good. thanks for ur help tho kimmeh!

 

[fashionista]

oooh tanks u lainee! that explained it al thank u thank u!

 

[Supra]

Originally posted by Lainee
No, you cannot simply cancel the square root and the square. When you remove them you get y=|(x^2)-9| (where the bars are absolute values in case it wasn't clear )
So that's why it's just the quadratic drawn with the negative parts flipped up.

when u remove it, y do u get absolute values???is it coz the function has to b positive or something

 

[Xayma]

Originally posted by Supra
when u remove it, y do u get absolute values???is it coz the function has to b positive or something

Because it doesnt have a sign infront of the squareroot sign, it is looking only for positive values, the reason it is an absolute value is that the function inside the square root is ^2 and hence wont get a negative value underneath for x<3, x>-3, the values must be positive.

 

[Xayma]

And the graph looks like this in case your interested:

(Youll need to make the picture full size or it wont turn out right)

 

[Supra]

thanks xayma, which graphing program do u use?

 

[Xayma]

Graphsight, you can use it after the "trial period". But to do circles you have to do a parametric which is pretty easy but not as easy as x²+y²=r² After the trial period it just comes up asking you to register it while your using it etc.