help wit locus q plz? (1 Viewer)

Trev

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hey can someone plz show me how to do this q plz - (if u can b bothered can u do the second one too plz)

Q1) Find the equation of the locus of point P(x,y) that moves so that it is equidistant from the x-axis and the y-axis

Q2) Find the equation of the locus of point P(x,y) that moves so that the ratio of PA to PB is 3:2 where A = (-6,5) and B= (3,-1)


Answers (so u can check if u did it right)
A1)y=+x, -x A2)5x² - 102x + 5y² + 58y - 154 = 0

thanx cya :D
 

CM_Tutor

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(1) The distance from P(x, y) to the x-axis is |y|, and the distance to the y-axis is |x|. These distances are the same, so the locus is |y| = |x|, or y = +/- x.

(2) PA<sup>2</sup> = (x + 6)<sup>2</sup> + (y - 5)<sup>2</sup>
PB<sup>2</sup> = (x - 3)<sup>2</sup> + (y + 1)<sup>2</sup>

Now PA / PB = 3 / 2 (given)
So, 2PA = 3PB
4PA<sup>2</sup> = 9PB<sup>2</sup>
4[(x + 6)<sup>2</sup> + (y - 5)<sup>2</sup>] = 9[(x - 3)<sup>2</sup> + (y + 1)<sup>2</sup>]
4[x<sup>2</sup> + 12x + 36 + y<sup>2</sup> - 10y + 25] = 9[x<sup>2</sup> - 6x + 9 + y<sup>2</sup> + 2y + 1]
4x<sup>2</sup> + 48x + 244 + 4y<sup>2</sup> - 40y = 9x<sup>2</sup> - 54x + 90 + 9y<sup>2</sup> + 18y

So, 5x<sup>2</sup> - 102x + 5y<sup>2</sup> +58y - 154 = 0, as required.
 

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