Question

Determine the centre (h,k) and the radius r of the circle: 4x^2 – x + 4y^2 – 7y – 9 = 0

Answer 1

write in (x-h)^2+(y-k)^2=r^2 form

Answer 2

that's it?

Answer 3

not going to divide by 4, complete the square and all that? c'mon myininaya!

Answer 4

you want me to do their problem?

Answer 5

well of course! the form is easy, it is getting there that is hard

Answer 6

how do i play this song on the piano? hit the right keys...

Answer 7

i figure they wanted to try first

Answer 8

yeah well this one is really ugly. maybe there is a typo?

Answer 9

but if you insist that i do it for them
\[(4x^2-x)+(4y^2-7y)=9\]
\[(4x^2-\frac{4}{4}x)+(4y^2-\frac{4}{4}*7y)=9\]
\[4(x^2-\frac{1}{4}x)+4(y^2+\frac{1}{4}*7y)=9\]
\[4(x^2-\frac{1}{4}x+(\frac{1}{2*4})^2)+4(y^2+\frac{7}{4}y+(\frac{7}{2*4})^2)=9+4*(\frac{1}{2*4})^2+4*(\frac{7}{2*4})^2\]
\[4(x-\frac{1}{8})^2+4(y+\frac{7}{8})^2=9+4*\frac{1}{64}+4*\frac{49}{64}\]
\[4(x-\frac{1}{8})^2+4(y+\frac{7}{8})^2=9+\frac{1}{16}+\frac{49}{16}\]
\[4(x-\frac{1}{8})^2+4(y+\frac{7}{8})^2=9*\frac{16}{16}+\frac{50}{16}\]
\[4(x-\frac{1}{8})^2+4(y+\frac{7}{8})^2=\frac{194}{16}\]
\[\frac{1}{4}[4(x-\frac{1}{8})^2+4(y+\frac{7}{8})^2]=\frac{1}{4}*\frac{196}{16}\]
\[(x-\frac{1}{8})^2+(y+\frac{7}{8})^2=\frac{49}{16}\]

Answer 10

Center is \[(\frac{1}{8},-\frac{7}{8})\]
\[r^2=\frac{49}{16}=> r=\frac{7}{4}\]

Answer 11

Thanks for you help :)

Answer 12

http://alturl.com/452gu

Answer 13

that must have kept you busy

Answer 14

not really it was easy

Answer 15

interesing wikepedia
and my answer have a different radius

Answer 16

oops i see my center is diffent too i changed something that i wasnt suppose to

Answer 17

yeah i cheated too at first. that is why i said it was really ugly. but maybe i entered it wrong

Answer 18

a minus to a plus

Answer 19

kept you occupied for a while though, didn't it?

Answer 20

see second to third i changed something

Answer 21

no it didn't

Answer 22

but i got the wrong answer lol

Answer 23

like always

Answer 24

i would have divided by 4 first

Answer 25

http://openstudy.com/users/satellite73#/users/satellite73/updates/4e4056bd0b8bfb83f3cbf936

Answer 26

we could have done that first

Answer 27

i'm not typing that over again just to show john my mistake

Answer 28

he can read this and he can make the correction himself

Answer 29

no don't bother

Answer 30

btw did you notice that the wiz gave ictrees a medal?

Answer 31

lol

Answer 32

why is the radius different though?

Answer 33

no lol

Answer 34

my radius and wikepedia's radius differ by like .03125

Answer 35

(x-\frac{1}{8})^2+(y-\frac{7}{8})^2=\frac{49}{16}
i think this is suppose to be it

Answer 36

it got
\[\sqrt{\frac{97}{32}}\]

Answer 37

darn

Answer 38

\[(x-\frac{1}{8})^2+(y-\frac{7}{8})^2=\frac{49}{16}\]

Answer 39

really?

Answer 40

hmmm

Answer 41

yes

Answer 42

let me look at this again

Answer 43

complete the square is a pain that is why

Answer 44

and that is why we all love
\[-\frac{b}{2a}\]

Answer 45

ok wikepedia is right lol

Answer 46

its hard to beat a computer

Answer 47

you must be tired.
especially if you are calling wolfram wiki

Answer 48

oh lol

Answer 49

yes they are both w words

Answer 50

i am too. off to bed.

Answer 51

i got them confused

Answer 52

i like my wrong radius better thought since it had a pretty answer

Answer 53

though*

Answer 54

it was nicer :)

Answer 55

why are teachers so mean
algebra students can't do this

Answer 56

i don't know

Answer 57

my students would hate me for those fractions

Answer 58

yep...that's for sure

Answer 59

i am sure your students think you are cute

Answer 60

lol
i hope they do
because thats what im there for

Answer 61

to look cute

Answer 62

i remember when i was a student correcting my teachers when they made a mistake
it made me feel so smart

Answer 63

it gave me a high

Answer 64

i hate when i make mistakes

Answer 65

zarkon i see a fun problem

Answer 66

I don't make mistakes...I make it look like I'm making a mistake to see if my students are paying attention ;) (at least that is what I tell them )

Answer 67

where is that

Answer 68

lol