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TS EAMCET · Maths · Circle

The line \(x+y+1=0\) intersects the circle \(x^2+y^2-4 x+2 y-4=0\) at the points A and B. If \(M\) \((a, b)\) is the midpoint of AB , then \(a-b=\)

  1. A \(0\)
  2. B \(1\)
  3. C \(2\)
  4. D \(3\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(3\)

Step-by-step Solution

Detailed explanation

\(x+y+1=0 \Rightarrow y=-x-1\) Solving for point of intersection \(\begin{aligned} & x^2+(-x-1)^2-4 x+2(-x-1)-4=0 \\ & 2 x^2-4 x-5=0 ; x_1+x_2=2 \Rightarrow \frac{x_1+x_2}{2}=a=1 \\ & a+b+1=0 \Rightarrow b=-2 \therefore a-b=3 \end{aligned}\)