document.write( "Question 189592This question is from textbook saxon algebra 2
\n" ); document.write( ": Find the inverse of the matrix, if it exists.
\n" ); document.write( "[4 -2]
\n" ); document.write( "[-5 5]
\n" ); document.write( "I worked it out to:
\n" ); document.write( "x=(4)(5)-(-2)(-2)=20-4=16
\n" ); document.write( "x^-1=1/16 matrix [5 2] and [5 4] on the bottom.
\n" ); document.write( "What now? \n" ); document.write( "
Algebra.Com's Answer #142270 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
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Solved by pluggable solver: Finding the Inverse of a 2x2 Matrix

To find the inverse of the matrix \"A=%28matrix%282%2C2%2C4%2C-2%2C-5%2C5%29%29\", we can follow these steps:

Step 1) Find the determinant



The determinant of \"%28matrix%282%2C2%2C4%2C-2%2C-5%2C5%29%29\" is \"abs%28matrix%282%2C2%2C4%2C-2%2C-5%2C5%29%29=10\". So this means that \"d=10\"

Step 2) Swap the values



Now switch the highlighted values \"%28matrix%282%2C2%2Chighlight%284%29%2C-2%2C-5%2Chighlight%285%29%29%29\" to get \"%28matrix%282%2C2%2Chighlight%285%29%2C-2%2C-5%2Chighlight%284%29%29%29\"

Step 3) Change the sign



Now change the sign of the highlighted values \"%28matrix%282%2C2%2C5%2Chighlight%28-2%29%2Chighlight%28-5%29%2C4%29%29\" to get \"%28matrix%282%2C2%2C5%2Chighlight%282%29%2Chighlight%285%29%2C4%29%29\"

Step 4) Multiply by the inverse of the determinant



Multiply by \"1%2Fd\" to get \"%281%2Fd%29%28matrix%282%2C2%2C5%2C2%2C5%2C4%29%29\"

Plug in \"d=10\" to get \"%281%2F10%29%28matrix%282%2C2%2C5%2C2%2C5%2C4%29%29\"

Step 5) Multiply \"1%2F10\" by every element in the matrix (simplify and reduce if possible)



Multiply \"1%2F10\" by EVERY element to get

Multiply to get \"%28matrix%282%2C2%2C5%2F10%2C2%2F10%2C5%2F10%2C4%2F10%29%29\"

Reduce each element: \"%28matrix%282%2C2%2C1%2F2%2C1%2F5%2C1%2F2%2C2%2F5%29%29\"


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Answer:

So the inverse of \"%28matrix%282%2C2%2C4%2C-2%2C-5%2C5%29%29\" is \"%28matrix%282%2C2%2C1%2F2%2C1%2F5%2C1%2F2%2C2%2F5%29%29\"

This means that if \"A=%28matrix%282%2C2%2C4%2C-2%2C-5%2C5%29%29\" then \"A%5E%28-1%29=%28matrix%282%2C2%2C1%2F2%2C1%2F5%2C1%2F2%2C2%2F5%29%29\"
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