Actually i fink i've solved it YAY ...sori...how do i delete this thread?
A pt P(x,y) moves so that its distance from (3,4) is proportional to its distance from (-1,2). Find the equation of the locus of P if the origin is a pt on the locus.
I seriously have no clue how to do this q. - i tried using direct variation i.e.
then subbing k into
Naturally it didn't work =P
Thanx a lot.
Is this how u do it? Mayb it's wrong because the textbook's answer is actually instead of
Let pt (3,4) be A and pt (-1,2) be B.
AP is proportional to BP.
So is proportional to .
Therefore, AP = k × BP
Substitute in (0,0)
9 + 16 = k (1+4)
25 = 5k
Therefore, k = 5
Substitute k = 5 into the original equation.
The books answer would be correct if the second point was (1, 2) rather than (-1, 2) , so maybe there's a typo somewhere.