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Rotating the axes by 45° changes 3x² + 2xy + 3y² = 8 into
A4x'² + 2y'² = 8
B3x'² + 3y'² = 8
C2x'² + 4y'² = 8
Dx'² + 2y'² = 4
Answer & Solution
Correct answer: A. 4x'² + 2y'² = 8
With x² + y² = x'² + y'² and xy = (x'² - y'²)/2, the equation becomes 4x'² + 2y'² = 8.
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