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TS EAMCET · Maths · Pair of Lines

If \(4 x^2+12 x y+9 y^2+2 \mathrm{~g} x+2 \mathrm{f} y-1=0\) represent a pair of parallel lines then

  1. A \(\frac{f}{g}+\frac{g}{f}+\frac{13}{6}=0\)
  2. B \(\mathrm{f}^2+\mathrm{g}^2=\mathrm{fg}\)
  3. C \(\mathrm{f}^2+\mathrm{g}^2=6 \mathrm{fg}\)
  4. D \(\frac{f}{g}+\frac{g}{f}=\frac{13}{6}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\frac{f}{g}+\frac{g}{f}=\frac{13}{6}\)

Step-by-step Solution

Detailed explanation

Given equation: \( 4 x^2+12 x y+9 y^2+2 g x+2 f y-1=0 \) Compare with \( (a x+b y+c_1)(a x+b y+c_2)=0 \) \( (a x+b y)^2+(c_1+c_2)(a x+b y)+c_1 c_2=0 \) \( a^2 x^2+2 a b x y+b^2 y^2+a(c_1+c_2) x+b(c_1+c_2) y+c_1 c_2=0 \) By comparing coefficients: \( a^2=4 \implies a=2 \)…