document.write( "Question 110183This question is from textbook Algebra II Tennessee Edition
\n" ); document.write( ": I cannot find the solution to -5, 10, -15, 20, .... \n" ); document.write( "
Algebra.Com's Answer #80276 by solver91311(24713)\"\" \"About 
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First notice that the sign on each term alternates and the odd numbered terms are negative. That means a good place to start is to have each term contain the factor \"%28-1%29%5En\", which yields a positive 1 for all even n, and a negative 1 for all odd n.
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\n" ); document.write( "The next thing to notice is that the absolute value of each element increases by 5 each subsequent element, so 5n is a good expression for that.
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\n" ); document.write( "Putting it all together you get:
\n" ); document.write( ":
\n" ); document.write( "\"%28-1%29%5En%2A5n\"
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\n" ); document.write( "Check:
\n" ); document.write( "\"%28-1%29%5E1%2A5%2A1=%28-1%29%2A5=-5\"
\n" ); document.write( "\"%28-1%29%5E2%2A5%2A2=1%2A5%2A2=10\"
\n" ); document.write( "\"%28-1%29%5E3%2A5%2A3=%28-1%29%2A5%2A3=-15\"
\n" ); document.write( "\"%28-1%29%5E4%2A5%2A4=5%2A4=20\"
\n" ); document.write( ":
\n" ); document.write( "And the 5th term should be:
\n" ); document.write( "\"%28-1%29%5E5%2A5%2A5=%28-1%29%2A5%2A5=-25\"
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\n" ); document.write( "Exercise for the student: What would you do if your series had the odd terms positive and the even terms negative, i.e. the exact opposite of the problem given?
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