Question

What is the center and radius of the circle with the equation x2 + y2 + 8x - 4y - 61 = 0?

Answer 1

Use Completion Of Square Method here..

Answer 2

just rearrange the equation and try to make it in (x-x1)+(y-y1)= r^2

Answer 3

Missing squares !!!!

Wow...

Answer 4

oh sorry ....

Answer 5

Ghazi means : Make the equation looks like:

\[(x - h)^2 + (y-k)^2 = r^2\]
Here: \((h, k)\) is center and \(r\) is radius..

Answer 6

@Qawi when will you participate??

When we will get offline ??

Answer 7

i got ( 4,2) radius = 9

Answer 8

(x^2+8x+4)+(y^2-4y+2)- 6=61 ...i have rearranged and added four and two....so now you can do this...yes you're right

Answer 9

but radius = sqrt 67

Answer 10

thanks :-)

Answer 11

Wait...

Answer 12

Center is not right..

Answer 13

and you've forgotten one more thing here...that is sign of coordinates

Answer 14

it's (-4,2)

Answer 15

@waterineyes am i right?

Answer 16

Yes but in radius @Qawi is right..

Answer 17

Radius is 9...

Answer 18

how radius is 9?

Answer 19

let me tripple check

Answer 20

There you will add or subtract \(4^2\) and not 4..

Answer 21

srry dissconnected but as i was saying i dont think it would be -4 , 2 because that wlld be the equain for x2 + y2 - 8x - 4y - 61 = 0? We're looking for x2 + y2 + 8x - 4y - 61 = 0

Answer 22

no i guess radius is sqrt 67

Answer 23

+ 8x - 4y

half those terms and negate them

Answer 24

if you were looking for the equation of the circle in standard form ... then youd have to go all out; but the center parts are just the negation of half the "linear" terms for x and y

Answer 25

(x+4)^2 - (x-2)^2?

Answer 26

pfft, it says center AND radius ..... then yes, water was correct ;)

Answer 27

lol so its (-4,2); Radius =9

Answer 28

Yep..