document.write( "Question 478045: I am currently working on my summer math packet and I am stuck on this word problem \"If 5 times the square of an integer is decreased by 32 times the number the result is 21. Find the number.\" \n" ); document.write( "
Algebra.Com's Answer #327566 by MathLover1(20849)\"\" \"About 
You can put this solution on YOUR website!

\n" ); document.write( "let's the number be \"x\"\r
\n" ); document.write( "\n" ); document.write( "If 5 times the square of an integer \"5x%5E2\" \r
\n" ); document.write( "\n" ); document.write( "is decreased by \"32\" times the number \"5x%5E2-32x\"\r
\n" ); document.write( "\n" ); document.write( "the result is \"21\"...->\"5x%5E2-32x=21\"....solve quadratic\r
\n" ); document.write( "\n" ); document.write( "\"5x%5E2-32x-21=0\"...use quadratic formula\r
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Solved by pluggable solver: Quadratic Formula
Let's use the quadratic formula to solve for x:

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\n" ); document.write( " Starting with the general quadratic
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\n" ); document.write( " \"ax%5E2%2Bbx%2Bc=0\"
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\n" ); document.write( " the general solution using the quadratic equation is:
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\n" ); document.write( " \"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29\"
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\n" ); document.write( " So lets solve \"5%2Ax%5E2-32%2Ax-21=0\" ( notice \"a=5\", \"b=-32\", and \"c=-21\")
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\n" ); document.write( " \"x+=+%28--32+%2B-+sqrt%28+%28-32%29%5E2-4%2A5%2A-21+%29%29%2F%282%2A5%29\" Plug in a=5, b=-32, and c=-21
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\n" ); document.write( " \"x+=+%2832+%2B-+sqrt%28+%28-32%29%5E2-4%2A5%2A-21+%29%29%2F%282%2A5%29\" Negate -32 to get 32
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\n" ); document.write( " \"x+=+%2832+%2B-+sqrt%28+1024-4%2A5%2A-21+%29%29%2F%282%2A5%29\" Square -32 to get 1024 (note: remember when you square -32, you must square the negative as well. This is because \"%28-32%29%5E2=-32%2A-32=1024\".)
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\n" ); document.write( " \"x+=+%2832+%2B-+sqrt%28+1024%2B420+%29%29%2F%282%2A5%29\" Multiply \"-4%2A-21%2A5\" to get \"420\"
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\n" ); document.write( " \"x+=+%2832+%2B-+sqrt%28+1444+%29%29%2F%282%2A5%29\" Combine like terms in the radicand (everything under the square root)
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\n" ); document.write( " \"x+=+%2832+%2B-+38%29%2F%282%2A5%29\" Simplify the square root (note: If you need help with simplifying the square root, check out this solver)
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\n" ); document.write( " \"x+=+%2832+%2B-+38%29%2F10\" Multiply 2 and 5 to get 10
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\n" ); document.write( " So now the expression breaks down into two parts
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\n" ); document.write( " \"x+=+%2832+%2B+38%29%2F10\" or \"x+=+%2832+-+38%29%2F10\"
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\n" ); document.write( " Lets look at the first part:
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\n" ); document.write( " \"x=%2832+%2B+38%29%2F10\"
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\n" ); document.write( " \"x=70%2F10\" Add the terms in the numerator
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\n" ); document.write( " \"x=7\" Divide
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\n" ); document.write( " So one answer is
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\n" ); document.write( " \"x=7\"
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\n" ); document.write( " Now lets look at the second part:
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\n" ); document.write( " \"x=%2832+-+38%29%2F10\"
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\n" ); document.write( " \"x=-6%2F10\" Subtract the terms in the numerator
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\n" ); document.write( " \"x=-3%2F5\" Divide
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\n" ); document.write( " So another answer is
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\n" ); document.write( " \"x=-3%2F5\"
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\n" ); document.write( " So our solutions are:
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\n" ); document.write( " \"x=7\" or \"x=-3%2F5\"
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\n" ); document.write( "\n" ); document.write( "check our solutions:\r
\n" ); document.write( "\n" ); document.write( "\"x=7\" \r
\n" ); document.write( "\n" ); document.write( "\"5%2A7%5E2-32%2A7=21\"\r
\n" ); document.write( "\n" ); document.write( "\"5%2A49-224=21\"\r
\n" ); document.write( "\n" ); document.write( "\"245-224=21\"\r
\n" ); document.write( "\n" ); document.write( "\"21=21\"\r
\n" ); document.write( "\n" ); document.write( "or \"x=-3%2F5\"\r
\n" ); document.write( "\n" ); document.write( "\"5%2A%28-3%2F5%29%5E2-32%2A%28-3%2F5%29=21\"\r
\n" ); document.write( "\n" ); document.write( "\"5%2A%289%2F25%29%2B32%2A%283%2F5%29=21\"\r
\n" ); document.write( "\n" ); document.write( "\"45%2F25%2B96%2F5=21\"\r
\n" ); document.write( "\n" ); document.write( "\"1.8%2B19.2=21\"\r
\n" ); document.write( "\n" ); document.write( "\"21=21\"\r
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