Question

(7√2-9)(7√2+9) simplify​

Answer 1

Answer:

using identity (a+b)(a-b)= a^2 - b^2

(7√2-9)(7√2+9)= (7√2)^2 - 9^2

= 98-81

= 17

Hope it helps.......

Answer 2

$\boxed{\tt{(7 \sqrt{2} -9)(7 \sqrt{2} +9) = 17}}$

Consider,

$a= 7 \sqrt{2} \: and \: b = 9$

So, the expression is in the form of,

$(a - b)(a + b)$

And we know that,

$(a - b)(a + b) = {a}^{2} - {b}^{2}$

$\therefore (7 \sqrt{2} -9)(7 \sqrt{2} +9)$

$= {(7 \sqrt{2})}^{2} - {(9)}^{2}$

$= 98 - 81$

$= 17$

Regards,

@9thPlanet