中等MATH-ALGE-007
Factorise 2x^2 + 7x + 3.
A. (2x + 1)(x + 3)✓ 答案
B. (2x + 3)(x + 1)
C. (2x − 1)(x − 3)
D. (x + 1)(x + 3)
解說
(2x + 1)(x + 3) = 2x^2 + 6x + x + 3 = 2x^2 + 7x + 3. The factorisation (2x + 3)(x + 1) gives middle term 5x. (x + 1)(x + 3) is not quadratic with leading coefficient 2.