Which ones are in the second quadrant?

Question

anonymous · Answer

attachment

zzr0ck3r · Answer

so a point (a,b) is in the 2nd quadrant if a is negative and b is positive

zzr0ck3r · Answer

you with me?

anonymous · Answer

Right.

zzr0ck3r · Answer

the equation of a circle is $r^2=(x-\color{blue}{a})^2+(y-\color{blue}{b})^2$

zzr0ck3r · Answer

still with me?

zzr0ck3r · Answer

the minus signs are important here...

anonymous · Answer

That's the same thing as $$y ^{2}+x ^{2}=2(r)^{2}$$?

zzr0ck3r · Answer

no

anonymous · Answer

Isn't it when it's in a ( ) that means it's the opposite of what I see?

anonymous · Answer

Oh.

zzr0ck3r · Answer

I dont know where you keep getting that from

anonymous · Answer

I think I'm confusing formulas.

anonymous · Answer

I'll use the equation for a circle for this problem, then.

zzr0ck3r · Answer

use the equation I gave and look at your answers

example the first one
$(x+2)^2+(y-5)^2=9$
we should rewrite it so that we have a minus sign
$(x-(-2))^2+(y-5)^2=9$ 
so $a = -2$ 
and $b = 5$
and like I said if a is negative and b is positive the center is in the 2nd quadrant

anonymous · Answer

Okay. I got that.

zzr0ck3r · Answer

the important part is that you realize why I rewrote it with the negative sign, and that is because that is the form we need to get it into before we can see what the value of a and b are.

zzr0ck3r · Answer

so what is the sign of a and b in the second one?

anonymous · Answer

x is positive and y is negative?