AP ICET 2017 Shift 2 Paper

Question : 116 of 200

Marks: +1, -0

If the lines

ax+2y+1=0,bx+3y+1=0

and

cx+4y+1=0

are concurrent then a, b and c are in

Solution:

For the given three lines to be concurrent,

|\table a,2,1;b,3,1;c,4,1|

⇒a(3-4)-2(b-c)+(4b-3c)=0

⇒-a-2b+2c+4b-3c=0

⇒-a+2b-c=0

⇒b={a+c}/2

Hence, a, b and c are in an arithmetic progression (A.P.).

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