Question:

If \[ \frac{2x+5}{(x-1)(x+3)} = \frac{A}{x-1}+\frac{B}{x+3}, \] then \(A+B=\)

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In partial fractions, after taking LCM, compare coefficients of like powers of \(x\).
  • \(-2\)
  • \(2\)
  • \(1\)
  • \(-1\)
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The Correct Option is B

Solution and Explanation

Concept:
This is a partial fraction problem. We compare coefficients after taking common denominator.

Step 1:
Given: \[ \frac{2x+5}{(x-1)(x+3)} = \frac{A}{x-1}+\frac{B}{x+3} \]

Step 2:
Take LCM on the right side: \[ \frac{A}{x-1}+\frac{B}{x+3} = \frac{A(x+3)+B(x-1)}{(x-1)(x+3)} \]

Step 3:
Since denominators are same, compare numerators: \[ 2x+5=A(x+3)+B(x-1) \]

Step 4:
Expand: \[ 2x+5=Ax+3A+Bx-B \] \[ 2x+5=(A+B)x+(3A-B) \]

Step 5:
Compare coefficient of \(x\): \[ A+B=2 \] \[ \boxed{2} \]
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