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Basic of Logarithms
easy
If ${{3x + 4} \over {{{(x + 1)}^2}(x - 1)}} = {A \over {(x - 1)}} + {B \over {(x + 1)}} + {C \over {{{(x + 1)}^2}}}$, then $A = $
A
$-0.5$
B
$3.75$
C
$1.75$
D
$-0.25$
Solution
(c) We have, ${{3x + 4} \over {{{(x + 1)}^2}(x – 1)}} = {A \over {(x – 1)}} + {B \over {(x + 1)}} + {C \over {{{(x + 1)}^2}}}$
==> $3x + 4 = A{(x + 1)^2}$+$B(x + 1)\,(x – 1) + C(x – 1)$
Putting $x = 1$, we get $7 = A{(2)^2}$ ==> $A = {7 \over 4}$.
Standard 11
Mathematics