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Factorisation — MATHS STD 8 — Question

ICSE BoardEnglish MediumSTD 8MATHSFactorisation3 Marks
Question
Factorise: $a^2 - b^2 - 2b - 1$
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Answer

$a^2 - b^2 - 2b - 1$
$= a^2 - (b^2 + 2b + 1)$
$...[(a + b)^2 = a^2 + b^2 + 2ab]$
$...[a^2 - b^2 = (a + b) (a - b)]$
$= (a)^2 - (b + 1)^2$
$= (a + b + 1)(a - b - 1)$

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