AMC 8 1998 Problem 2

AMC8 1998 年第 2 题

表达式与运算★☆☆☆☆

If

\begin{pmatrix} a & b \\ c & d \end{pmatrix} = ad - bc

, then

\begin{pmatrix} 2 & 1 \\ 1 & 3 \end{pmatrix} + \begin{pmatrix} 3 & 2 \\ 1 & 4 \end{pmatrix} =

若

\begin{pmatrix} a & b \\ c & d \end{pmatrix} = ad - bc

，则

\begin{pmatrix} 2 & 1 \\ 1 & 3 \end{pmatrix} + \begin{pmatrix} 3 & 2 \\ 1 & 4 \end{pmatrix} =

A.-2
B.-1
C.0
D.1
E.2

正确答案 · Correct Answer

E

解析 · Solution

Solution 1

Plugging in values for

a

,

b

,

c

, and

d

, we get

a=3, b=4, c=1, d=2,

a\times d=3×2=6

,

b\times c=4×1=4

, 6-4=2,

E

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