If the point P(a, b, c), with reference to (i), lies on the plane 2x+y+z=1, then the value of 7a+b+c is
[abc]⎡⎢⎣197827737⎤⎥⎦=[000]
So, we get the equations
a+8b+7c=0 .....(1)
9a+2b+3c=0 .....(2)
7a+7b+7c=0 or a+b+c=0 .....(3)
Let c=k , then
⇒b=−6k7,a=−k7
Equation of plane 2a+b+c=1
⇒k=−7
⇒a=1,b=6,c=−7
⇒7a+b+c=6