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AP EAMCET · Maths · Straight Lines

Let a, b and c be distinct and none of them is equal to 1. If the lines x+ay+a=0 bx+y+b=0 and cx+cy+1=0 are concurrent, then the value of aa-1+bb-1+cc-1 is

  1. A -1
  2. B 1
  3. C 2
  4. D 0
Verified Solution

Answer & Solution

Correct Answer

(A) -1

Step-by-step Solution

Detailed explanation

We know that, three lines a1x+b1y+c1=0 a2x+b2y+c2=0 a3x+b3y+c3=0 are concurrent if a1b1c1a2b2c2a3b3c3=0 Therefore, given lines are concurrent if 1aab1bcc1=0 Expanding along R1, we have 11-bc-ab-bc+abc-c=0 or ab+bc+ca=1+2abc  ...i Now, aa-1+bb-1+cc-1…