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Mathematics 18 Online
OpenStudy (anonymous):

Darn Systems of equations...

OpenStudy (anonymous):

\[x ^{2}+x^2=9 and x^2 + (y-2)^2 =1\]

OpenStudy (anonymous):

there's gonna be two answers

OpenStudy (anonymous):

i think

OpenStudy (abb0t):

is the first one \(y^2+x^2\) ?

OpenStudy (anonymous):

no

OpenStudy (anonymous):

oh it is

OpenStudy (anonymous):

i just checked

OpenStudy (anonymous):

@abb0t ?

OpenStudy (abb0t):

I don't know how to do this. Let me find you a math prodigy to help you.

OpenStudy (anonymous):

it is y^2 + x^2

OpenStudy (anonymous):

intersection of 2 circles, there will be 2 points. from 1st, you get x^2 = 9-y^2 substitute this in 2nd equation to get a quadratic in y

OpenStudy (anonymous):

i never thought of it as the intersection of 2 circles...im not sure how u got that though @gohangoku58

OpenStudy (anonymous):

x^2+y^2=9 subtracting y^2 from both sides, x^2 +y^2-y^2 = 9-y^2 x^2+0=9-y^2 x^2 =9-y^2 thats how...

OpenStudy (anonymous):

you could just graph them both...

OpenStudy (anonymous):

@gohangoku58 okay i see. do u substitute left or right side of the equal sign in the second equation?

OpenStudy (anonymous):

so, for 2ns equation, u have 9-y^2 + (y-2)^2=1 can you simplify this ? you'll get a simple linear equation.

OpenStudy (anonymous):

expand (y-2)^2

OpenStudy (anonymous):

kk

OpenStudy (anonymous):

so \[2y^2 - 4y + 12\] ?

OpenStudy (anonymous):

=0

OpenStudy (anonymous):

and then i solve for y with the quadratic formula?

OpenStudy (anonymous):

doesn't y^2 getting cancelled ?

OpenStudy (anonymous):

**isn't

OpenStudy (anonymous):

dang of course

OpenStudy (anonymous):

so y=-3?

OpenStudy (anonymous):

yes :)

OpenStudy (anonymous):

kewl

OpenStudy (anonymous):

so what am i supposed to do with this information?

OpenStudy (anonymous):

do i plug y into an original equation?

OpenStudy (anonymous):

find x y= -3 put this in x^2+y^2 =9 yes!

OpenStudy (anonymous):

so x=0?

OpenStudy (anonymous):

wait! i am gettting y= 3 !

OpenStudy (anonymous):

-4y+12 = 0 4y=12 y=3

OpenStudy (anonymous):

then, yes, x=0

OpenStudy (anonymous):

kk

OpenStudy (anonymous):

i forgot to to have the -'s cancel out..

OpenStudy (anonymous):

so, the solution is 0,3

OpenStudy (anonymous):

only.

OpenStudy (anonymous):

kk, thx!

OpenStudy (anonymous):

welcome ^_^

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