document.write( "Question 1021526: I need help with the following:\r
\n" ); document.write( "\n" ); document.write( "Multiply and then simplify completely: (3√7−5√5)(3√7+5√5)\r
\n" ); document.write( "\n" ); document.write( "I have come up with several answer and I am having trouble showing my work \n" ); document.write( "

Algebra.Com's Answer #637288 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let $\"+x+=+3%2Asqrt%287%29+\"$
\n" ); document.write( "Let $\"+y+=+5%2Asqrt%285%29+\"$
\n" ); document.write( "--------------------
\n" ); document.write( " $\"+%28+3%2Asqrt%287+%29+-+5%2Asqrt%285%29%29%2A%28+3%2Asqrt%287+%29+%2B+5%2Asqrt%285%29+%29+\"$
\n" ); document.write( "Make this substitution:
\n" ); document.write( " $\"+x+-+y+%29%2A%28+x+%2B+y+%29+=+x%5E2+-+y%5E2+\"$
\n" ); document.write( "---------------------------
\n" ); document.write( " $\"+x%5E2+=+9%2A7+\"$
\n" ); document.write( " $\"+x%5E2+=+63+\"$
\n" ); document.write( "and
\n" ); document.write( " $\"+y%5E2+=+25%2A5+\"$
\n" ); document.write( " $\"+y%5E2+=+125+\"$
\n" ); document.write( "----------------
\n" ); document.write( " $\"+x%5E2+-+y%5E2+=+63+-+125+\"$
\n" ); document.write( " $\"+x%5E2+-+y%5E2+=+-62+\"$
\n" ); document.write( "------------------
\n" ); document.write( "check answer:
\n" ); document.write( "I'll do it with calculator:
\n" ); document.write( "

\n" ); document.write( " $\"+sqrt%287%29+=+2.6458+\"$
\n" ); document.write( " $\"+sqrt%285%29+=+2.2361+\"$
\n" ); document.write( " $\"+%28+3%2A2.6458+-+5%2A2.2361+%29%2A%28+3%2A2.6458+%2B+5%2A2.2361+%29+=+-62+\"$
\n" ); document.write( " $\"+%28+7.9374+-+11.1805+%29%2A%28+7.9374+%2B+11.1805+%29+=+-62+\"$
\n" ); document.write( " $\"+%28+-3.2431%29%2A%28+19.1179+%29+=+-62+\"$
\n" ); document.write( " $\"+-62.0013+=+-62+\"$
\n" ); document.write( "I assume the error is due to rounding off \n" ); document.write( "

\n" );