→ 向量与矩阵 SC04 Matrices ★★☆☆☆ 基础 MCQ

SC04 Matrices 练习题

SC04 Matrices Practice Question

3. 已知 $(m \quad 5) \begin{pmatrix} -6 & n \\ m & 4 \end{pmatrix} = (2 \quad 20)$。求 $m$ 的值。 A $3$ B $2$ C $-1$ D $-2$

📌 考点：Matrices · 难度：基础

📌 Topic: Matrices · Difficulty: 基础

Perform matrix multiplication: $(m \times -6 + 5 \times m \quad m \times n + 5 \times 4) = (2 \quad 20)$.

This simplifies to $(-6m + 5m \quad mn + 20) = (2 \quad 20)$, so $(-m \quad mn + 20) = (2 \quad 20)$.

Equating the first corresponding elements: $-m = 2 \Rightarrow m = -2$.

To check, $mn + 20 = 20 \Rightarrow mn = 0$. Since $m = -2$, $n$ must be 0.

🦆 想做更多 Matrices 题目？

🦆 Want more Matrices practice?

鸭鸭数学有完整题库，AI 即时批改，免费使用。

DuckMath has a full question bank with instant AI grading — free to use.

→ 向量与矩阵

→ Vectors & Matrices

此题属于统考 SC04，单元：向量与矩阵，考点：Matrices，难度：基础。

Subject: SC04 · Unit: Vectors & Matrices · Topic: Matrices · Level: 基础.

💡 解题小贴士

💡 Quick Tips