document.write( "Question 27911: Please help me solve this problem.\r
\n" ); document.write( "\n" ); document.write( "(5 + 3i)* (2 + i) \n" ); document.write( "

Algebra.Com's Answer #15218 by bmauger(101) $\"\"$ $\"About$

You can put this solution on YOUR website!
For the most part, you can treat i's just like x's (it's only when we get to i^2 that we have to do anything differently).\r
\n" ); document.write( "\n" ); document.write( "So we start by using FOIL to get:
\n" ); document.write( " $\"%285%2B3i%29%282%2Bi%29=5%2A2%2B5%2Ai%2B3i%2A2%2B3i%2Ai=10%2B11i%2B3i%5E2\"$
\n" ); document.write( "The difference now comes in that i^2 term at the end. Since i is the imaginary number defined by $\"i=sqrt%28-1%29\"$ then $\"i%5E2=-1\"$ so whenever you see an i^2 term, replace it with a negative 1:
\n" ); document.write( " $\"10%2B11i%2B3%28-1%29\"$
\n" ); document.write( " $\"10%2B11i-3\"$
\n" ); document.write( " $\"7%2B11i\"$ \n" ); document.write( "

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