document.write( "Question 531041: x(to the fourth) +8x(squared)+15=0 \n" ); document.write( "

Algebra.Com's Answer #350311 by oberobic(2304) $\"\"$ $\"About$

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Let u = x^2.
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\n" ); document.write( "u^2 +8u +15 = 0
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\n" ); document.write( "(u+3)(u+5)=0
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\n" ); document.write( "substitute u = x^2
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\n" ); document.write( "(x^2 + 3)(x^2 + 5) = 0
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\n" ); document.write( "So x^2 = -3 or -5. That means there are no real roots.
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