F actorise - 81 x 2-1 A- 1-9 x1-9 xB- 1-9 x1-9 xC- 9 x-19 x-1D- 9 x-19 x-1

The correct option is C (9x + 1)(9x 1)The given expression nbsp;81x^2 1 nbsp;can be written as, 81x^2 1=(9x)^2 (1)^2 [Using the identity: a^2 b^2=(a+b)(a ...

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Standard VIII

Mathematics

Factorisation Using Algebraic Identities

F actorise : ...

Question

$F a c t o r i s e : 81 x^{2} - 1$

(1 - 9 x) (1 + 9 x)

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(1 - 9 x) (1 - 9 x)

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(9 x + 1) (9 x - 1)

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(9 x - 1) (9 x - 1)

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Solution

The correct option is C $(9 x + 1) (9 x - 1)$
The given expression $81 x^{2} - 1$ can be written as,
$81 x^{2} - 1 = (9 x)^{2} - (1)^{2}$
$[Using the identity: a^{2} - b^{2} = (a + b) (a - b)]$
$= (9 x + 1) (9 x - 1)$

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Factorise: 81x2−1

The correct option is C (9x+1)(9x−1)The given expression 81x2−1 can be written as, 81x2−1=(9x)2−(1)2 [Using the identity: a2−b2=(a+b)(a−b)] =(9x+1)(9x−1)

$F a c t o r i s e : 81 x^{2} - 1$

The correct option is C $(9 x + 1) (9 x - 1)$
The given expression $81 x^{2} - 1$ can be written as,
$81 x^{2} - 1 = (9 x)^{2} - (1)^{2}$
$[Using the identity: a^{2} - b^{2} = (a + b) (a - b)]$
$= (9 x + 1) (9 x - 1)$