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ECAT Mathematics QUESTION #783
Question 1
If \(ax^2 + 2hxy + by^2 = 0\), their lines are orthogonal when:
  • \(a + b = 0\)✔️
  • \(a - b = 0\)
  • \(a = b\)
  • None
Correct Answer Explanation
For the pair of lines \(ax^2 + 2hxy + by^2 = 0\) to be perpendicular, the sum of coefficients of \(x^2\) and \(y^2\) must be zero: \(a + b = 0\).