Show that x 2 +2x+1 is O(x 2 ) if x>1, x 2 +2x+1 2, x 2 +2x+1 1, x 2 +2x 2 +x 2

Show that x²+2x+1 is O(x²)

if x>1, x²+2x+12+2x²+x²=4x²

if x>2, x²+2x+12+x²+x²=3x²

Why x>1, x²+2x²+x² ?

Why x>2, x²+x²+x²?