The equation of a circle which passes through the points of intersection of the circles \[ 2x^2 + 2y^2 - 2x + 6y - 3 = 0, \quad x^2 + y^2 + 4x + 2y + 1 = 0 \] and whose centre lies on the common chord of these circles is:
\( 4x^2 + 4y^2 + 6x + 10y - 1 = 0 \)
Step 1: Finding the Equation of the Common Chord
The given circles are: \[ 2x^2 + 2y^2 - 2x + 6y - 3 = 0, \] \[ x^2 + y^2 + 4x + 2y + 1 = 0. \] Subtracting the second equation from the first: \[ (2x^2 + 2y^2 - 2x + 6y - 3) - (x^2 + y^2 + 4x + 2y + 1) = 0. \] \[ x^2 + y^2 - 6x + 4y - 4 = 0. \]
Step 2: Finding the Required Circle
A circle passing through the intersection of these two given circles is of the form: \[ S_1 + \lambda S_2 = 0. \] Substituting and simplifying using the condition that the center lies on the common chord, we derive: \[ 4x^2 + 4y^2 + 6x + 10y - 1 = 0. \]
Step 3: Conclusion
Thus, the final answer is: \[ \boxed{4x^2 + 4y^2 + 6x + 10y - 1 = 0}. \]
A rectangle is formed by the lines \[ x = 4, \quad x = -2, \quad y = 5, \quad y = -2 \] and a circle is drawn through the vertices of this rectangle. The pole of the line \[ y + 2 = 0 \] with respect to this circle is:
S = (-1,1) is the focus, \( 2x - 3y + 1 = 0 \) is the directrix corresponding to S and \( \frac{1}{2} \) is the eccentricity of an ellipse. If \( (a,b) \) is the centre of the ellipse, then \( 3a + 2b \) is:
Given the vectors:
\[ \mathbf{a} = \mathbf{i} + 2\mathbf{j} + \mathbf{k} \]
\[ \mathbf{b} = 3(\mathbf{i} - \mathbf{j} + \mathbf{k}) = 3\mathbf{i} - 3\mathbf{j} + 3\mathbf{k} \]
where
\[ \mathbf{a} \times \mathbf{c} = \mathbf{b} \]
\[ \mathbf{a} \cdot \mathbf{x} = 3 \]
Find:
\[ \mathbf{a} \cdot (\mathbf{x} \times \mathbf{b} - \mathbf{c}) \]
If three numbers are randomly selected from the set \( \{1,2,3,\dots,50\} \), then the probability that they are in arithmetic progression is:
A student has to write the words ABILITY, PROBABILITY, FACILITY, MOBILITY. He wrote one word and erased all the letters in it except two consecutive letters. If 'LI' is left after erasing then the probability that the boy wrote the word PROBABILITY is: \