Question

Find the value of k, if the x² + 3xy + 2y² + x - y + k = 0 represent a pair of lines.

Answer 1

x² + kx + 16 = 0

According to,

D = B² - 4AC

k² - 4 × 1 × 16

k² = 64

If D > 0 , it will have real roots.

D > 0 => K² - 64 > 0

k² > 64

k > +8 or -8 !!