Mathematics
18 Online
OpenStudy (anonymous):
Darn Systems of equations...
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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
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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
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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?
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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
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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?
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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!
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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
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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 ^_^