Ni

Ko b

A = x² + 2y² - 2xy + 2x - 6y + 2028 = (x² - 2xy + y²) + 2x - 6y + y² + 2028 = (x-y)² + 2(x-y) + 1 + (y² - 4y + 4) + 2023 = (x-y+1)² + (y-2)² + 2023 => Min A = 2023 khi x-y+1=0 và y-2=0 => x = 1, y = 2 💡

3x(x - 1) - 1 + x = 0

⇔ 3x(x-1) + (x-1) = 0

⇔ (x-1)(3x+1) = 0

=> x = 1

a) x² + 25 - 10x = x² - 10x + 25 = (x - 5) Mũ 2 8y³ + x³ = (2y)³ + x³ = (2y + x)(4y² - 2xy + x²)

(2x + 1)² = (2x)² + 2(2x)(1) + 1² = 4x² + 4x + 1 (a - b/2)³ = a³ - 3a²(b/2) + 3a(b/2)² - (b/2)³ = a³ - (3/2)a²b + (3/4)ab² - b³/8