Find the equation of family of planes through the line of intersection of the planes 3x – y + 2z = 4 and x + y + z = 2 which is passing through (2, 2, 1)?

The equation of the family of planes through the line of intersection of planes


3x – y + 2z = 4 and x + y + z = 2 is,


(3x – y + 2z – 4) + k(x + y + z – 2) = 0 ……(1)


If it passes through (2, 2, 1) then,


(6 – 2 + 2 – 4) + k(2 + 2 + 1 – 2) = 0


k = –


Substituting k = – in eq.(1) We get,


7x – 5y + 4z = 0 as the equation of the required plane.


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