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Engineering Maths · Q80

Linear Algebra

Engineering and GATE · Engineering Maths · question 80

Q80

The inverse of the 2 × 2 matrix \[ [ array*20c 1&2 \\ 5&7 array ]\] is

The inverse of the 2 × 2 matrix \left[ {\begin{array}{*{20}{c}} 1&2 \\ 5&7 \end{array}} \right]  is
A.
\frac{1}{3}\left[ {\begin{array}{*{20}{c}} { - 7}&2 \\ 5&{ - 1} \end{array}} \right]
Answer
B.
\frac{1}{3}\left[ {\begin{array}{*{20}{c}} 7&2 \\ 5&1 \end{array}} \right]
C.
\frac{1}{3}\left[ {\begin{array}{*{20}{c}} 7&{ - 2} \\ { - 5}&1 \end{array}} \right]
D.
\frac{1}{3}\left[ {\begin{array}{*{20}{c}} { - 7}&{ - 2} \\ { - 5}&{ - 1} \end{array}} \right]

Answer: Option A

Solution

Answer: Option A
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