Let ax+by+c=0 be a variable straight line, where a, b and c are 1st, 3rd and 7th terms of some increasing A.P. Then the variable straight line always passes through a fixed point which lies on

Explanation

Given equation
`ax+by+c=0−−−−−`(1)

Here a,b,c are 1st,3rd,7th terms of increasing A.P

Hence `b=a+2` and `c=a+6`

From equation (1)

`ax+(a+2)y+(a+6)=0`

Here on putting `x=2,y=−3 `the above equation is satisfied

Hence fixed point is `(2,3)`
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