Question

$(x - 9)(x + 9)$
​

Answer 1

Answer:

(x - 9) (x + 9)

= (x² - 9²)

=  x² - 81

__________

Identity used →

(a² - b²)

= (a + b)(a - b)

____________

Answer 2

Given Algebraic Expression : $\sf{(x-9)(x+9)}$

What to be Done : Simplify the Given Expression

$\bf{--------------------------@KingSrikar}$

Step by Step Solution :

We have a formula for calculating such problems $\sf{(a+b)(a-b)=a^2-b^2}$ And Now We can Substitute the values given in our Problem instead of $\sf{a}$ and $\sf{b}$

$\to\sf{(x-9)(x+9)}$     (Here a = x and b = 9)

$\to\sf{x^2-9^2}$    (Using Formula $\sf{(a+b)(a-b)=a^2-b^2}$)

$\to\sf{x^2-81}$      ↔    Required Answer