document.write( "Question 338972: Please help me solve this equation: \r
\n" ); document.write( "\n" ); document.write( "determine the second and fifth terms in the expanison of (2x-3y)^5?
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Algebra.Com's Answer #242977 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( "\"%282x-3y%29%5E5\" Start with the given expression\r
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\n" ); document.write( "\n" ); document.write( "To expand this, we're going to use binomial expansion. So let's look at Pascal's triangle:
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1   

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1   1   

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1   2   1   

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1   3   3   1   

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1   4   6   4   1   

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1   5   10   10   5   1   
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\n" ); document.write( "\n" ); document.write( "Looking at the row that starts with 1,5, etc, we can see that this row has the numbers:\r
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\n" ); document.write( "\n" ); document.write( "1, 5, 10, 10, 5, and 1\r
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\n" ); document.write( "\n" ); document.write( "These numbers will be the coefficients of our expansion. So to expand \"%282x-3y%29%5E5\", simply follow this procedure:\r
\n" ); document.write( "\n" ); document.write( "Write the first coefficient. Multiply that coefficient with the first binomial term \"2x\" and then the second binomial term \"-3y\". Repeat this until all of the coefficients have been written.\r
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\n" ); document.write( "\n" ); document.write( "Once that has been done, add up the terms like this:\r
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\n" ); document.write( "\n" ); document.write( " Notice how the coefficients are in front of each term.\r
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\n" ); document.write( "\n" ); document.write( "However, we're not done yet.\r
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\n" ); document.write( "\n" ); document.write( " Looking at the first term \"1%282x%29%28-3y%29\", raise \"2x\" to the 5th power and raise \"-3y\" to the 0th power.\r
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\n" ); document.write( "\n" ); document.write( " Looking at the second term \"5%282x%29%28-3y%29\" raise \"2x\" to the 4th power and raise \"-3y\" to the 1st power.\r
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\n" ); document.write( "\n" ); document.write( "Continue this until you reach the final term.\r
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\n" ); document.write( "\n" ); document.write( "Notice how the exponents of \"2x\" are stepping down and the exponents of \"-3y\" are stepping up.\r
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\n" ); document.write( "\n" ); document.write( "So the fully expanded expression should now look like this:\r
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\n" ); document.write( "\n" ); document.write( " Distribute the exponents\r
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\n" ); document.write( "\n" ); document.write( "\"32x%5E5-240x%5E4y%2B720x%5E3y%5E2-1080x%5E2y%5E3%2B810xy%5E4-243y%5E5\" Multiply the terms with their coefficients\r
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\n" ); document.write( "\n" ); document.write( "So \"%282x-3y%29%5E5\" expands and simplifies to \"32x%5E5-240x%5E4y%2B720x%5E3y%5E2-1080x%5E2y%5E3%2B810xy%5E4-243y%5E5\".\r
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\n" ); document.write( "\n" ); document.write( "In other words, \"%282x-3y%29%5E5=32x%5E5-240x%5E4y%2B720x%5E3y%5E2-1080x%5E2y%5E3%2B810xy%5E4-243y%5E5\"\r
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\n" ); document.write( "\n" ); document.write( "From the last equation, we can see that the 2nd term is \"-240x%5E4y\" and the 5th term is \"810xy%5E4\"\r
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\n" ); document.write( "\n" ); document.write( "Shortcut: You can find the kth term of the expansion \"%28a%2Bb%29%5En\" by using the formula \"%28nCk%29%2Aa%5E%28n-k%29%2Ab%5Ek\" where \"nCk\" is the coefficient (either found with a calculator or by using Pascal's triangle).\r
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\n" ); document.write( "\n" ); document.write( "If you need more help, email me at jim_thompson5910@hotmail.com\r
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\n" ); document.write( "\n" ); document.write( "Also, feel free to check out my tutoring website. \r
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\n" ); document.write( "\n" ); document.write( "Jim
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