Question

factorise : a2-81
$factorise : a {}^{2} - 81$
​

Answer 1

Answer:

${a}^{2} - 81$

${(a)}^{2} - {(9)}^{2}$

$(a + 9)(a - 9)$

Ans. (a + 9) (a - 9)

Step-by-step explanation:

Here we have used the formula 'a^2 - b^2 = (a + b)(a - b)'

Hope it helps.

Answer 2

Answer:

$\huge\boxed{\boxed{\mathfrak\red{Answer}}}$

Step-by-step explanation:

= $a {}^2 - 81$

= $a {}^2 - 9 {}^2$

= $(a+9)×(a-9)$