Mathematics for IGCSE & O level - Algebraic Manipulation (Section 6 - No. 31)
Which of the following expressions are correctly expanded?
2(x + 1) = 2x + 2
3(x - 2) = 3x - 6
(x + 1)^2 = x^2 + 1
(x + 2)(x - 3) = x^2 - x - 6
คำอธิบาย
Correct expansions: 2(x + 1) = 2x + 2; 3(x - 2) = 3x - 6; (x + 2)(x - 3) = x^2 - x - 6. Incorrect: (x + 1)^2 = x^2 + 2x + 1