Question

A circle is defined by the following equation:
3x^(2)+3y^(2)+30x+30y+150=0
What is its radius?

Answer 1

divide all by 3

(x^2 +10x) + (y^2 +10y) = -50

Answer 2

now complete the squares of the x and y

(x^2 +10x +25) + (y^2 +10y +25) = -50-25-25

(x+5)^2 +(y+5)^2 = -100

are you sure it aint -150?

Answer 3

teh radius is most likely 10

Answer 4

or 0 lol

Answer 5

no, in the original equation, all numbers are positive.

Answer 6

-50+25+25=0 then

Answer 7

looks to be 0 for some reason

Answer 8

i gotta wonder, is 0 correct?

Answer 9

When dividing by 3, (x^(2)+10x)+(y^(2)+10y)=-50, how do you get 10x and 10y?

Answer 10

3(x^2 +10x+25)-75 +3(y^2 +10y+25)-75= -150

3(x^2 +10x+25) +3(y^2 +10y+25)= -150 +75+75 = 0

Answer 11

3*10 = 30 right?

Answer 12

I dont understand how you get rid of the x and y

Answer 13

i dint get rid of anything :) i moved them around to work with them easier, thats all

Answer 14

but if there's a variable on the left side of the equation, shouldnt there still be a variable on the right side?

Answer 15

Actually, shouldn't it remain -50-25-25, and not -50+25+25?