Mathematics for IGCSE & O level - Algebraic Manipulation (Section 3 - No. 4)
What expression results from completing the square of x² + 6x + 5?
(x + 3)² + 5
(x + 3)² - 4
(x - 3)² + 14
(x - 3)² - 14
Wyjaśnienie
Take half of the x coefficient (6/2=3), square that (3²=9). You will add and subtract 9: x² + 6x + 9 - 9 + 5 which = (x+3)² - 4.