Question

pls help...stuck with this problem..got it wrong already. thank you!
1) a circle has the equation x^2+y^2+8x-8y-17=0...graph the circle using the center (h,k) and radius r

2) What are the intercepts, if any?

Answer 1

here the center is (-4,4) and radius is 7
intercepts are (2*(33)^1/2,0) and (0,2*(33)^1/2)

Answer 2

hi vicky007! the first part all the way to graphing is the easier part but finding the intercepts always gets to me. i always seem to get the first half of it and not the last part (intercepts)...not sure what i'm doing wrong. thank you so much for your help. greatly appreciated!

Answer 3

well for finding the intercepts
just plug in 0 for either x or y

x-intercepts: y=0
-> x^2 +8x -17 =0
use quadratic formula

y-intercepts: x=0
-> y^2-8y-17 = 0
use quadratic formula

Answer 4

and if you put the equation in standard form first, then quadratic formula is unneccessary

Answer 5

oh wow, that makes a lot of sense now. still working on things by hand as i'm asking for help. i'm still trying to figure out my graphing calculator...but that makes a lot of sense...trying a new, similar exercise so i learn this. i'll take your advice on that. thank you!

Answer 6

did that help?
i probably should have started with equation in standard form
you said you didn't have any trouble using completing the square to get it in standard form

-> (x+4)^2 + (y-4)^2 = 49
then plug in zeroes to get intercepts

Answer 7

i get a different answer than vick

x = -4 +- sqrt(33)
y = 4 +- sqrt(33)

Answer 8

so sorry, laptop crashed...must've been the website...it was so slow earlier that i had to shut down laptop. thanks again for your help....i did the problem to verify and i also got the same answer. sorry i lost you there.

Answer 9

you all have abeen such great help.