what is the center and radius of the circle with the given equation? x^2+y^2+14x-12y=-69

Question

anonymous · Answer

so do you need the exact number or could you have x and y's?

anonymous · Answer

it would help me better if i had the numbers i would think

anonymous · Answer

uhh well you need 2 equations to solve for this mess and you now only have 1 equation which means that variable x and variable y can be some unfixed number

anonymous · Answer

oh okayy

anonymous · Answer

so do you have a second equation?

anonymous · Answer

on my study guide this is the question has its written out i just need some help

anonymous · Answer

you need to convert the equation to the form

(x - a)^2 + (y - b)^2 = r^2

this will have centre (a,b) and radius r

anonymous · Answer

oh yea what galli said

jdoe0001 · Answer

hmm skellz    do you know what a "perfect square trinomial" is?

anonymous · Answer

first convert x^2 + 14 to the form (x + c)^2 - d
and do similar coversion with y^2 - 12y

anonymous · Answer

x^2 + 14x = (x + 7)^2 - 49

anonymous · Answer

you have the 14   and then subtract the square of this half

anonymous · Answer

ok i went to the bathroom let me catch up with what yall are saying but no i dont know that that is

anonymous · Answer

ur formula comes down to $$(x^2+14x+49)-49+(y^2-12y+36)-36$$=-69

anonymous · Answer

yes

anonymous · Answer

move all the things over then you can factor into perfect squares so you can find the radius of your circle through $$x^2+y^2=r^2$$

anonymous · Answer

the perfect square is in the parentheses

anonymous · Answer

^

anonymous · Answer

can you finish this now? or do u need more help

anonymous · Answer

ok omm

anonymous · Answer

i got an answer but not sure if its right

anonymous · Answer

what is it?

anonymous · Answer

center at (7,-6) radius 16

anonymous · Answer

your final equation should be

( x + 7)^2 + ( x + 6)^2 = 85 - 69  = 16

not quite  7 = -a ( see the standard equation) and   6 = -b)  , 16 = r^2

so a = -7, b = -6 and r = 4

anonymous · Answer

ohhhhh

anonymous · Answer

get it?

anonymous · Answer

appreciate it

anonymous · Answer

yw

anonymous · Answer

oh - i made an error   sorry

its (y - 6) ^2  not  (x+ 6(^2            - as its -12y

so b = 6

correct is  

center( -7,6)  and radius  4

anonymous · Answer

* not (y + 6)^2  as its -12y

anonymous · Answer

i got the sign wrong