MHT CET20249 May 2024Morning ShiftMathematicsPair of LinesActual
If an equation hxy + g x+ f y+ c =0 represents a pair of lines, then
Options
- Afg = ch
- Bgh = cf
- Cfh = cg
- Dhf =- cg
Correct answer
A. fg = ch
Step-by-step solution
Given equation of pair of lines is aligned & h x y+g x+f y+c=0 & A=0, B=0, C=c, F= f 2 , G= g 2 , H= h 2 aligned aligned & | array lll A & H & G H & B & F G & F & C array |=0 & | array ccc 0 & ~h 2 & ~g 2 ~h 2 & 0 & f 2 ~g 2 & f 2 & c array |=0 aligned aligned & -h 2 [ ch 2 - gf 4 ]+ g 2 [ hf 4 ]=0 & - h ^2 c 4 + hgf 8 + ghf 8 =0 & - h ^2 c 4 + hgf 4 =0 & ~h ^2 c = hgf & hc = gf aligned