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Basic of Logarithms
easy
જો ${9 \over {(x - 1)\,{{(x + 2)}^2}}} = {A \over {x - 1}} + {B \over {x + 2}} + {C \over {{{(x + 2)}^2}}}$ તો $A - B - C = $
A
$3$
B
$-1$
C
$5$
D
એકપણ નહીં
Solution
(c) $9 = A{(x + 2)^2} + B(x – 1)\,(x + 2)\, + C\,(x – 1)$
For $x = 1,\,\,9 = 9A \Rightarrow A = 1$
For $x = – 2,\,9 = – 3C \Rightarrow C = – 3$
Equating coefficient of ${x^2},\,0 = A + B \Rightarrow B = – A = – 1$
$\therefore A – B – C = 1 – ( – 1) – ( – 3) = 1 + 1 + 3 = 5$.
Standard 11
Mathematics