document.write( "Question 1104176: If 4^x+2(2^x)=80 what is the value of x? \n" ); document.write( "

Algebra.Com's Answer #718914 by ikleyn(52851) $\"\"$ $\"About$

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\n" ); document.write( " $\"4%5Ex+%2B+2%282%5Ex%29\"$ = 80 \r
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document.write( "Introduce new variable u = .  Then your original equation becomes this quadratic equation\r\n" );
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document.write( " = 0.\r\n" );
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document.write( "To solve, factor left side\r\n" );
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document.write( "(u-8)*(u+10) = 0.\r\n" );
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document.write( "It has the roots  u = 8  and  u = -10.\r\n" );
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document.write( "So, according our substitution,\r\n" );
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document.write( "    = 8  with the solution x = 3,\r\n" );
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document.write( "or\r\n" );
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document.write( "    = -10,  which has no solutions.\r\n" );
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document.write( "Answer.  The solution is x = 3.\r\n" );
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