Question

Find the point(s) of intersection:
x^2 + y^2 = 25
xy = 12

Answer 1

Have you considered substitution?

From the second, x = 12/y -- Go!

Answer 2

I tried, but I do not know how to evaluate 144/y^2 + y^2 = 25

Answer 3

http://www.wolframalpha.com/input/?i=144%2Fy^2+%2B+y^2+%3D+25

Answer 4

\[\frac{y^4+144}{y^2}=25\]
\[y^4+144=25y^2\]
\[y^4-25y^2+144=0\]

Answer 5

What did you try? Can you solve 144/x+ x = 25?

Answer 6

From y^4 - 25^2 + 144 = 0 would you factor? If so, how?