Exercise · ZW-ZERO-DIVISOR-005 · ★☆☆ Basic
In the ring of \(2\times2\) real matrices, which of these matrices is a zero divisor?
Choose one option.
Show answer
- C. \(\begin{pmatrix}1&0\\0&0\end{pmatrix}\)
Explanation
The matrix with a single 1 in the upper left corner is nonzero and singular (determinant 0), and its product with \(\begin{pmatrix}0&0\\0&1\end{pmatrix}\) is the zero matrix. The other three have nonzero determinant, so they are units.
Review the concept: Zero divisor
A zero divisor of a ring \(R\) is an element \(a\neq0\) for which there is another element \(b\neq0\) of \(R\) whose product with \(a\) is zero.
\[ab=0,\quad a\neq0,\ b\neq0\]
More practice problems: zero divisor
- ZW-ZERO-DIVISOR-001 In ℤ_12, which of these elements is a zero divisor?
- ZW-ZERO-DIVISOR-002 How many zero divisors does ℤ_10 have?
- ZW-ZERO-DIVISOR-003 Which of these rings has no zero divisors?
- ZW-ZERO-DIVISOR-004 In ℤ_15, which b≠0 satisfies 6b=0?
- ZW-ZERO-DIVISOR-006 Which statement is true in a ring R with identity, R≠0?
- ZW-ZERO-DIVISOR-007 In ℤ×ℤ, which of these elements is a zero divisor?
- ZW-ZERO-DIVISOR-008 In ℤ_8, which pair with x≠ y satisfies 4x=4y?
- ZW-ZERO-DIVISOR-009 How many zero divisors does ℤ_21 have?