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Determinants

Question
CBSEENMA12034747
Wired Faculty App

Use matrix method to solve the system of equations:
3x + 5y = 8
2x - y = 1

Solution

The given equations are
3x + 5y = 8
2x – y = 1
These equations can be written as
                    open square brackets table row 3 cell space space space space space space 5 end cell row 2 cell space space minus 1 end cell end table close square brackets space space open square brackets table row straight x row straight y end table close square brackets space equals open square brackets table row 8 row 1 end table close square brackets
or       AX space equals space straight B space where space straight A space equals space open square brackets table row 3 cell space space space space space space 5 end cell row 2 cell space minus 1 end cell end table close square brackets comma space space space space space straight X space equals space open square brackets table row straight x row straight y end table close square brackets comma space space space straight B space equals space open square brackets table row 8 row 1 end table close square brackets space space space space space space space space space space space space space space space space space space space space space open vertical bar straight A close vertical bar equals space open vertical bar table row 3 cell space space space space space space 5 end cell row 2 cell space minus 1 end cell end table close vertical bar space equals space minus 3 minus 10 space equals space minus 13 space not equal to space 0 therefore space space space space space straight A to the power of negative 1 end exponent space exists. space space space space space space space space space space space space space space space space space straight A subscript 11 space equals negative 1 comma space space space straight A subscript 12 space equals negative 2 comma space space space straight A subscript 21 space equals space minus 5 comma space space space straight A subscript 22 space equals space 3 therefore space space space space space space space space space space adj. space straight A space equals space open square brackets table row cell negative 1 end cell cell space space minus 2 end cell row cell negative 5 end cell cell space space space space 3 end cell end table close square brackets to the power of apostrophe space equals space open square brackets table row cell negative 1 end cell cell space space space minus 5 end cell row cell negative 2 end cell cell space space space space space space 3 end cell end table close square brackets space space space space space space space space space space space space space space space space space space space space space space space straight A to the power of negative 1 end exponent space space equals space fraction numerator adj space straight A over denominator open vertical bar straight A close vertical bar. end fraction space equals space minus 1 over 13 open square brackets table row cell negative 1 end cell cell space space space space minus 5 end cell row cell negative 2 end cell cell space space space space space 3 end cell end table close square brackets Now space space space space AX space space equals straight B space space space space space space space space rightwards double arrow space space space space space straight X space equals space straight A to the power of negative 1 end exponent straight B space rightwards double arrow space space space space space space space space open square brackets table row straight x row straight y end table close square brackets space equals space minus 1 over 13 open square brackets table row cell negative 1 end cell cell space space space minus 5 end cell row cell negative 2 end cell cell space space space space space 3 end cell end table close square brackets space open square brackets table row 8 row 1 end table close square brackets space space space space rightwards double arrow space space space space space open square brackets table row straight x row straight y end table close square brackets space space equals negative 1 over 13 open square brackets table row cell negative 8 minus 5 end cell row cell negative 16 plus 3 end cell end table close square brackets rightwards double arrow space space space space space space space space space open square brackets table row straight x row straight y end table close square brackets space equals space minus 1 over 13 open square brackets table row cell negative 13 end cell row cell negative 13 end cell end table close square brackets space space space rightwards double arrow space space space space space space open square brackets table row straight x row straight y end table close square brackets space equals space open square brackets table row 1 row 1 end table close square brackets therefore space space space space straight x space equals space 1 comma space space space space straight y space equals space 1 space space space space space space space

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