gwd29 29 舊帖新問

Kath1985

Q29:

For which real numbers x is the expression 2/(x-2)(x+1)not defined?



A.x = 0 only

B.x = 2 only

C.x = –1 only

D.x = –1 or 2

E.x = –1, 0, or 2

Answer: D

查過前人的解釋如下  但還是不明白題目要問的是什麼 且 為什麼是D
當X=-1 or 2, 2/(x-2)(x+1)分母是零, 整個值就成為無限大無法定義

B. x = 2 only ...沒有考慮到x=-1
C. x = –1 only ...沒有考慮到x=2
E. x = –1, 0, or 2 ...x=0,整項等於-1

kNIGHTaTR

分数分母不可为0.