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AP EAMCET · Maths · Pair of Lines

If lx2+3xy-2y2-5x+5y+k=0 represents a pair of perpendicular lines, then

  1. A k=±3, l=±2
  2. B k=-22, l=-12
  3. C k=-3, l=2
  4. D k=-16, l=9
Verified Solution

Answer & Solution

Correct Answer

(C) k=-3, l=2

Step-by-step Solution

Detailed explanation

lx2+3xy-2y2-5x+5y+k=0 if lines are perpendicular then, l-2=0 ⇒l=2 2x2+3xy-2y2-5x+5y+k=0 it represents a pair of lines a=2,  b=-2,  c=k h=32, f=52,  g=-52 abc+2fgh-af2-bg2-ch2=0 ⇒-4k-754-504+2x254-9k4=0 ⇒25k=-75 ⇒k=-3