MHB Prove 9999999+1999000 is Composite Number

[anemone]

Prove that the number $9999999+1999000$ is composite.

 

[kaliprasad]

Spoiler: my Solution

Let x = 1000 to keep it simple
So we get
$9999999+1999000 = 10^7-1 + 1999 * 1000$
$= 10 * 10^ 6 - 1+ (2000-1)* 1000$
$= 10 x^2 - 1 + (2x-1) x$ putting 1000 = x
$=12x^2 - x - 1$
$= (4x+1)(3x-1)$
$= 4001 * 2999$ putting back x = 1000

Hence it is composite