Mathematics for IGCSE & O level - Algebraic Manipulation (Section 6 - No. 28)
When completing the square, what must be added and subtracted to an expression of the form x² + bx?
(b/2) and (b/2)
(b/2)² and (b/2)²
(b/2)² and -(b/2)²
b² and -b²
คำอธิบาย
We add and subtract (b/2)² to complete the square, to maintain the value.