find equation of line passing through P(1,2) and intersecting X+Y=5,2X+y=7 at A,B resp PA PB harmonic mean is 10

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at A,B resp PA PB harmonic mean is 10

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Could you please elaborate on what this refers to?

The lines x+y=5 and 2x+y=7 intersect at (2,3).

Since the line needed passes through (1,2), we can have it intersect where the other two lines intersect. This means it passes through
(1,2) and (2,3). One line would be y=x+1


But, a harmonic mean is the number of terms divided by the sum of the reciprocals of those terms.
As to what the harmonic mean and PB refers to, I do not know.

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Originally Posted by galactus

Could you please elaborate on what this refers to?.

The lines x+y=5 and 2x+y=7 intersect at (2,3).

Since the line needed passes through (1,2), we can have it intersect where the other two lines intersect. This means it passes through
(1,2) and (2,3). One line would be y=x+1


But, a harmonic mean is the number of terms divided by the sum of the reciprocals of those terms.
As to what the harmonic mean and PB refers to, I do not know.

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PA^(-1)+pb^(-1)=10
the answer is to be in the form of y-2=tana(x-1) where tan(A)=-----