document.write( "Question 95958: I have been trying to do this problem for a while now, i tried doing it step by step and also checking it on the calculator but it gives me a different answer every time.\r
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\n" ); document.write( "\n" ); document.write( "3square root of 45 -2square root of 125\r
\n" ); document.write( "\n" ); document.write( "this is al together like side by side
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Algebra.Com's Answer #69895 by bucky(2189)\"\" \"About 
You can put this solution on YOUR website!
Given to simplify:
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\n" ); document.write( "\"3%2Asqrt%2845%29-2%2Asqrt%28125%29\"
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\n" ); document.write( "On a calculator you can find that the square root of 45 is 6.708203932 so multiplying
\n" ); document.write( "the square root of 45 times 3 results in 3*6.708203932 = 20.1246118. Substituting this number
\n" ); document.write( "into the problem in place of \"3%2Asqrt%2845%29\" reduces the problem to:
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\n" ); document.write( "\"20.1246118+-+2%2Asqrt%28125%29\"
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\n" ); document.write( "Next you can use the calculator to find that \"sqrt%28125%29+=+11.18033989\". Multiplying this
\n" ); document.write( "by -2 results in \"-2%2Asqrt%28125%29+=+-2%2A11.18033989+=+-22.36067977\". Then substituting this
\n" ); document.write( "into the equation reduces the equation to:
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\n" ); document.write( "\"20.1246118+-+22.36067977+=+-2.236067975\"
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\n" ); document.write( "So the answer to this problem is -2.236067975 within the roundoff error on the last decimal
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\n" ); document.write( "Now let's work the problem without doing it on a calculator. Start with:
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\n" ); document.write( "\"3%2Asqrt%2845%29-2%2Asqrt%28125%29\"
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\n" ); document.write( "Note that by the rules of radicals, \"sqrt%2845%29+=+sqrt%289%2A5%29+=+sqrt%289%29%2Asqrt%285%29+=+3%2Asqrt%285%29\"
\n" ); document.write( "So you can substitute \"3%2Asqrt%285%29\" for \"sqrt%2845%29\" to get:
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\n" ); document.write( "\"3%2A3%2Asqrt%285%29+-+2%2Asqrt%28125%29\"
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\n" ); document.write( "Now let's simplify \"sqrt%28125%29\":
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\n" ); document.write( "\"sqrt%28125%29+=+sqrt%2825%2A5%29+=+sqrt%2825%29%2Asqrt%285%29=+5%2Asqrt%285%29\"
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\n" ); document.write( "You can now substitute \"5%2Asqrt%285%29\" for \"sqrt%28125%29\" to get:
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\n" ); document.write( "\"3%2A3%2Asqrt%285%29+-+2%2A5%2Asqrt%285%29\"
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\n" ); document.write( "Do the multiplications. 3*3 = 9 and -2*5 = -10. So this becomes:
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\n" ); document.write( "\"9%2Asqrt%285%29+-+10%2Asqrt%285%29\"
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\n" ); document.write( "You can factor \"sqrt%285%29\" from each term to get:
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\n" ); document.write( "\"%289-10%29%2Asqrt%285%29\"
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\n" ); document.write( "Combine the two numbers in the parentheses to get:
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\n" ); document.write( "\"%28-1%29%2Asqrt%285%29+=+-1%2Asqrt%285%29+=+-sqrt%285%29\"
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\n" ); document.write( "So the answer we got is \"-sqrt%285%29\". If you find the square root of 5 on a calculator
\n" ); document.write( "you will find that it is 2.236067977. Therefore, our answer becomes:
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\n" ); document.write( "\"-sqrt%285%29+=+-2.236067977\"
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\n" ); document.write( "This agrees with the answer we got by doing all the work on a calculator. So you can use
\n" ); document.write( "either method depending on what is compatible with the way your teacher wants it done.
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\n" ); document.write( "Hope this helps you to understand the problem and how to get the answer.
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