Mathematics for IGCSE & O level - Algebraic Manipulation (Section 6 - No. 21)
What is the result of completing the square for x² - 4x + 5?
(x - 2)² + 1
(x + 2)² + 1
(x - 4)² + 5
(x - 2)² - 1
คำอธิบาย
To complete the square, we take half the coefficient of x, square it, and add and subtract it within the expression.