Question 823171
1. x^2+y^2=16 y=-x^2-4
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x^2 = y-4
Substitute for "x^2" and solve for "y":
y-4 + y^2 = 16
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y^2 + y - 20 = 0
Factor:
(y+5)(y-4) = 0
y = -5 or y = 4
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Solve for "x":
x^2 = y-4
If y = -5, x^2 = -9 
Therefore y = -5 is extraneous.
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If y = 4, x^2 = 4-4 = 0
Then x = 0
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Solution:: (0,4)
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2. 
x^2-y^2=61 
x^2-y^2=11
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Subtract to get:
0 = 50
That is a contradiction.
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There are no solutions.
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Cheers,
Stan H.
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