document.write( "Question 1204792: Find the value of a if 7^a -7^a-5 = 117642√7 \n" ); document.write( "
Algebra.Com's Answer #841281 by math_tutor2020(3817)\"\" \"About 
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\n" ); document.write( "I'll assume the equation is \"7%5Ea+-+7%5E%28a-5%29+=+117642%2Asqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "It can be rewritten to \"7%5Ea+-+7%5E%28-5%29%2A7%5Ea+=+117642%2Asqrt%287%29\" and then to \"x+-+7%5E%28-5%29%2Ax+=++117642%2Asqrt%287%29\" where \"x+=+7%5Ea\"\r
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\n" ); document.write( "\n" ); document.write( "Let's solve for x.
\n" ); document.write( "\"x+-+7%5E%28-5%29%2Ax+=++117642%2Asqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x%281+-+7%5E%28-5%29%29+=++117642%2Asqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x%281+-+1%2F%287%5E5%29%29+=++117642%2Asqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x%281+-+1%2F16807%29+=++117642%2Asqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x%2816807%2F16807+-+1%2F16807%29+=++117642%2Asqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x%28%2816807-1%29%2F16807%29+=++117642%2Asqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x%2816806%2F16807%29+=++117642%2Asqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=++%2816807%2F16806%29%2A117642%2Asqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=++117649%2Asqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "Notice how 7^6 = 117649
\n" ); document.write( "We can rewrite the right hand side as a power of 7.\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+117649%2Asqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+7%5E6%2A7%5E%281%2F2%29%5E%22%22\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+7%5E%286%2B1%2F2%29%5E%22%22\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+7%5E%2813%2F2%29%5E%22%22\"\r
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\n" ); document.write( "\n" ); document.write( "\"7%5Ea+=+7%5E%2813%2F2%29%5E%22%22\" plug in x = 7^a\r
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\n" ); document.write( "\n" ); document.write( "\"a+=+13%2F2\" The bases are both 7, so the exponents must be the same.
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