E(x) = (x²-x+2)² - (x²-x)² - (2x-1)²
= (x²-x+2)² - (x²-x)² - (x+x-1)²
= [x(x-1)+2]² - [x(x-1)]² - (x+x-1)²
Notez: x = a, x-1 = b
E = (ab+2)² - (ab)² - (a+b)²
= (ab)² + 4ab + 4 - (ab)² - a² - 2ab - b²
= -a² +2ab - b² + 4
= -(a-b)² + 4
= -[x-(x-1)]² + 4
= -1² + 4
= -1 + 4
= 3
⇒ E(x) = 3, ∀x ∈ ℝ
