(2−i)(−2+i)=(2-i)(-2+i)=
A. −3+4i-3+4i
B. −3-3
C. −5-5
D. −5+4i-5+4i

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Worked solution

1. 展开两个复数的多项式乘积

(2−i)(−2+i)=2×(−2)+2i+(−i)×(−2)+(−i)i=−4+2i+2i−i2(2-i)(-2+i) = 2 \times (-2) + 2i + (-i) \times (-2) + (-i)i = -4 + 2i + 2i - i^2

2. 利用 $i^2 = -1$ 进行化简,写成复数的代数表示形式形式

将 i2=−1i^2 = -1 代入上式得:
−4+4i−(−1)=−4+4i+1=−3+4i-4 + 4i - (-1) = -4 + 4i + 1 = -3 + 4i
结合选项,正确答案为 A。

Answer

A

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