Question

Choose correct alternatives:

If the equation 4x² + hxy + y² = 0 represents two coincident lines, then h = _______

Options

• ± 2

• ± 3

• ± 4

• ± 5

Answer 1

If the equation 4x² + hxy + y² = 0 represents two coincident lines, then h = ± 4.

Explanation:

ax² + 2hxy + by² = 0

a = 4, h = `"h"/2`, b = 1

h² − ab = 0

`("h"/2)^2 - 4 xx 1 = 0`

`"h"^2/4 = 4`

h² = 16

h = ± 4