Question Details

The value of k for (2k, 3k), (0, 0), (1, 0) and (0, 1) to be on the circle is

Options

A

2/13

B

5/13

C

1/13

D

2/13

Correct Answer :

5/13

Solution :

The correct option is 5/13.

To find the value of k such that the points (2k,3k), (0,0), (1,0), and (0,1) lie on the same circle, we can first determine the equation of the circle passing through the three known points: (0,0), (1,0), and (0,1).

The general equation of a circle is given by:
x2+y2+2gx+2fy+c=0

Step 1: Find the constants by substituting the coordinates of the known points.

1. Since the circle passes through the origin (0,0):
02+02+2g(0)+2f(0)+c=0c=0

2. Since the circle passes through (1,0):
12+02+2g(1)+2f(0)+0=0
1+2g=02g=-1

3. Since the circle passes through (0,1):
02+12+2g(0)+2f(1)+0=0
1+2f=02f=-1

Substituting the values of 2g, 2f, and c back into the general equation, we obtain the equation of the circle:
x2+y2-x-y=0

Step 2: Find the value of k using the fourth point.

Since the point (2k,3k) also lies on this circle, its coordinates must satisfy the circle's equation. Let us substitute x=2k and y=3k:
(2k)2+(3k)2-(2k)-(3k)=0

Simplifying the algebraic equation:
4k2+9k2-5k=0
13k2-5k=0
k(13k-5)=0

This gives us two possible solutions:
k=0 or 13k-5=0

Since k=0 represents the origin point (0,0) which is already on the circle, the non-zero value of k is given by:
13k=5k=513

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