AMC12 2003 B
AMC12 2003 B · Q1
AMC12 2003 B · Q1. It mainly tests Manipulating equations, Fractions.
Which of the following is the same as
\[\frac{2-4+6-8+10-12+14}{3-6+9-12+15-18+21}?\]
以下哪个与
\[\frac{2-4+6-8+10-12+14}{3-6+9-12+15-18+21}?\]
(A)
-1
-1
(B)
$-\frac{2}{3}$
$-\frac{2}{3}$
(C)
$\frac{2}{3}$
$\frac{2}{3}$
(D)
1
1
(E)
$\frac{14}{3}$
$\frac{14}{3}$
Answer
Correct choice: (C)
正确答案:(C)
Solution
\[\frac{2-4+6-8+10-12+14}{3-6+9-12+15-18+21}=\frac{2+(-4+6)+(-8+10)+(-12+14)}{3+(-6+9)+(-12+15)+(-18+21)}=\frac{2\cdot4}{3\cdot4}=\text {(C) } \frac{2}{3}\]
\[\frac{2-4+6-8+10-12+14}{3-6+9-12+15-18+21}=\frac{2+(-4+6)+(-8+10)+(-12+14)}{3+(-6+9)+(-12+15)+(-18+21)}=\frac{2\cdot4}{3\cdot4}=\text {(C) } \frac{2}{3}\]
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