document.write( "Question 58382: I cannot solve x^4-5x^2-8=0
\n" ); document.write( "My professor told me to substitute y for x but I still cannot fathom what is going on. I have tried for the past several hours please help.
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Algebra.Com's Answer #40002 by Nate(3500) $\"\"$ $\"About$

You can put this solution on YOUR website!
Depending on your math status, I could lead you onto what your professor was indicating.
\n" ); document.write( "y = x^2
\n" ); document.write( "leads to ~>
\n" ); document.write( "(x^2)^2 - 5(x^2) - 8 = 0
\n" ); document.write( "(y)^2 - 5(y) - 8 = 0
\n" ); document.write( "y^2 - 5y - 8 = 0
\n" ); document.write( " $\"y+=+%28-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"$
\n" ); document.write( " $\"y+=+%285+%2B-+sqrt%28+25+%2B+32+%29%29%2F%282%29+\"$
\n" ); document.write( " $\"y+=+%285+%2B-+sqrt%28+57+%29%29%2F%282%29+\"$
\n" ); document.write( "Now, we have the partial answer. Since the original equation supported $\"x\"$ , we must have the variable $\"x\"$ equal something to develop the answer.
\n" ); document.write( " $\"sqrt%28y%29+=+x\"$
\n" ); document.write( " $\"x+=+sqrt%28%285+%2B-+sqrt%28+57+%29%29%2F%282%29%29\"$
\n" ); document.write( "About:
\n" ); document.write( "x = 2.5050
\n" ); document.write( "x = -2.5050
\n" ); document.write( " $\"graph%28300%2C300%2C-10%2C10%2C-10%2C10%2Cx%5E4+-+5x%5E2+-+8%29\"$ \n" ); document.write( "

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