Exercise · ZW-CRAMERS-RULE-001 · ★☆☆ Basic
Use Cramer's rule to find \(x\) in \(\begin{cases}2x+y=7\\ x-y=-1\end{cases}\).
Choose one option.
Show answer
- C. \(x=2\)
Explanation
\(\det A=-3\) and \(x=\dfrac{\det\begin{pmatrix}7&1\\-1&-1\end{pmatrix}}{-3}=\dfrac{-6}{-3}=2\).
Review the concept: Cramer's rule
Cramer's rule gives the unique solution of a square system, whose coefficient matrix \(A\) has nonzero determinant, as a quotient of determinants.
\[x_i=\frac{\det A_i}{\det A}\]
More practice problems: cramer's rule
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