To solve the given problem, let's analyze the provided equations:
- The first equation is \(x^4 + x^2y^2 + y^4 = 8\).
- The second equation is \(x^2 + xy + y^2 = 4\).
We need to find the value of \(xy\).
Let's solve this step-by-step:
- Consider the identity: \((x^2 + y^2)^2 = x^4 + 2x^2y^2 + y^4\).
- Let's express \(x^4 + x^2y^2 + y^4\) using this identity:
- We can rewrite it as: \(x^4 + x^2y^2 + y^4 = (x^2 + y^2)^2 - x^2y^2\).
- From the second equation \(x^2 + xy + y^2 = 4\), we know \(x^2 + y^2\) can be expressed in terms of \(xy\):
- Squaring both sides of \(x^2 + xy + y^2 = 4\), we get:
- \((x^2 + xy + y^2)^2 = 16\)
- Expand to find:
\(x^4 + 2x^3y + 3x^2y^2 + 2xy^3 + y^4 = 16\)
- Now, notice:
\(x^4 + x^2y^2 + y^4 = (x^2 + y^2)^2 - x^2y^2 = 8\)
\((x^2 + y^2)^2 = 8 + x^2y^2\) (from the given equation). - Let \(s = x^2 + y^2\). Then \(s = 4 - xy\). From the identity:
\((4 - xy)^2 = 8 + x^2y^2\) (substituting). - Let's solve for \(xy\):
- \(16 - 8xy + (xy)^2 = 8 + (xy)^2\)
- Cancel \((xy)^2\) from both sides, then \(16 - 8xy = 8\).
- Simplify to find \(8 = 8xy\).
- Finally, \(xy = 1\).
Thus, the value of \(xy\) is 1. The correct answer is option: 1.