document.write( "Question 26058: ok, i just DONT understand imaginary numbers in problems! i really need help! heres a problem: 7i^3 + 8i^12 +9i^17 -5i^16 = ?\r
\n" ); document.write( "\n" ); document.write( "PLEASE HELP! i dont know what to do with the numbers in front...!!!
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Algebra.Com's Answer #14034 by Earlsdon(6294)\"\" \"About 
You can put this solution on YOUR website!
Imaginary numbers: In math, the lower-case letter i is used to stand for the square root of -1, thus: \"sqrt%28-1%29+=+i\"\r
\n" ); document.write( "\n" ); document.write( "If you multiply i times i or \"i%5E2\" this is the same as multiplying \"sqrt%28-1%29sqrt%28-1%29+=+%28sqrt%28-1%29%29%5E2\" = -1 so you can see that\"i%5E2+=+-1\"\r
\n" ); document.write( "\n" ); document.write( "Now if you keep doing this, that is, find \"i%5E3\",\"i%5E4\",\"i%5E5\", you begin to see a definite pattern:\r
\n" ); document.write( "\n" ); document.write( "\"i+=+sqrt%28-1%29\"
\n" ); document.write( "\"i%5E2+=+-1\"
\n" ); document.write( "\"i%5E3+=+i%28i%5E2%29\" = \"i%28-1%29+=+-i\"
\n" ); document.write( "\"i%5E4+=+i%28i%5E3%29\" = \"i%28-i%29+=+-i%5E2\" = \"-%28-1%29+=+1\"
\n" ); document.write( "\"i%5E5+=+i%28i%5E4%29\" = \"i%281%29+=+i\"
\n" ); document.write( "\"i%5E6+=+i%28i%5E5%29\" = \"i%28i%29+=+i%5E2\" = \"-1\"
\n" ); document.write( "\"i%5E7+=+i%28i%5E6%29\" = \"i%28-1%29+=+-i\" ...and so on.\r
\n" ); document.write( "\n" ); document.write( "Do you see it? Sometimes it's helpful to constuct a table for the values of \"i%5En\" for different values of n:
\n" ); document.write( "n----\"i%5En\"
\n" ); document.write( "--------------
\n" ); document.write( "1.....i
\n" ); document.write( "2....-1
\n" ); document.write( "3....-i
\n" ); document.write( "4.....1
\n" ); document.write( "5.....i
\n" ); document.write( "6....-1
\n" ); document.write( "7....-i
\n" ); document.write( "8.....1
\n" ); document.write( "9.....i
\n" ); document.write( "10...-1
\n" ); document.write( "11...-i
\n" ); document.write( "12....1
\n" ); document.write( "and so on
\n" ); document.write( "As for the number in front of the i's in your problem, you just multiply by that number. For example:
\n" ); document.write( "\"7i%5E3+=+7%28-i%29\" = \"-7i\"
\n" ); document.write( "\"8i%5E%2812%29+=+8%281%29\" = 8\r
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