Answer:
The factored form of x²-400 is (x+20)(x-20).
Step-by-step explanation:
Given the expression
[tex]x^2\:-\:400[/tex]
As the square of 20 is 400. Therefore, rewrite 400 as 20²
⇒ [tex]x^2-20^2[/tex]
[tex]\mathrm{Apply\:Difference\:of\:Two\:Squares\:Formula:\:}x^2-y^2=\left(x+y\right)\left(x-y\right)[/tex]
Thus, the expression becomes
[tex]x^2-20^2=\left(x+20\right)\left(x-20\right)[/tex]
Thus, the factored form of x²-400 is (x+20)(x-20).