document.write( "Question 169886: Please help me solve this equation: \"+2.79%5E%28x-1%29+-+4.377%5Ex+=+0+\". Thank you! \n" ); document.write( "
Algebra.Com's Answer #125305 by gonzo(654)\"\" \"About 
You can put this solution on YOUR website!
problem:
\n" ); document.write( "\"+2.79%5E%28x-1%29+-+4.377%5Ex+=+0+\"
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\n" ); document.write( "not sure if this is the correct way to approach this, but i got a solution and it appears to be good.
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\n" ); document.write( "you start off with:
\n" ); document.write( "\"2.79%5E%28x-1%29+-+4.377%5Ex+=+0\"
\n" ); document.write( "add 4.377^x to both sides of the equation:
\n" ); document.write( "\"2.79%5E%28x-1%29+=+4.377%5Ex\"
\n" ); document.write( "raise both sides of the equation to the \"%281%2F%28x-1%29%29\" exponent.
\n" ); document.write( "your equation becomes:
\n" ); document.write( "\"%282.79%5E%28x-1%29%29%5E%281%2F%28x-1%29%29+=+%284.377%5Ex%29%5E%281%2F%28x-1%29%29\"
\n" ); document.write( "simplify this and it becomes:
\n" ); document.write( "\"2.79%5E1+=+4.377%5E%28x%2F%28x-1%29%29\"
\n" ); document.write( "which is the same as:
\n" ); document.write( "\"2.79+=+4.377%5E%28x%2F%28x-1%29%29\"
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\n" ); document.write( "now that you have this in a standard exponential form, you should be able to solve it using logarithms.
\n" ); document.write( "you make use of two logarithmic formulas:
\n" ); document.write( "first formula:
\n" ); document.write( "\"y+=+a%5Ex\" if and only if \"log%28a%2Cy%29+=+x\"
\n" ); document.write( "second formula:
\n" ); document.write( "\"log%28a%2Cy%29+=+log%2810%2Cy%29+%2F+log%2810%2Ca%29\"
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\n" ); document.write( "using the first formula, your formula of:
\n" ); document.write( "\"2.79+=+4.377%5E%28x%2F%28x-1%29%29\"
\n" ); document.write( "becomes:
\n" ); document.write( "\"log%284.377%2C2.79%29+=+x%2F%28x-1%29\"
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\n" ); document.write( "using the second formula,
\n" ); document.write( "\"log%284.377%2C2.79%29+=+x%2F%28x-1%29\"
\n" ); document.write( "becomes:
\n" ); document.write( "\"%28log%2810%2C2.79%29+%2F+log%2810%2C4.377%29%29+=+x%2F%28x-1%29\"
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\n" ); document.write( "this becomes:
\n" ); document.write( "\".69497895+=+x%2F%28x-1%29\"
\n" ); document.write( "let the letter \"a\" represent \".69497895\" for now to make simplifying easier to show.
\n" ); document.write( "equation becomes:
\n" ); document.write( "\"a+=+x%2F%28x-1%29\"
\n" ); document.write( "multiply both sides of equation by (x-1)
\n" ); document.write( "\"a%2A%28x-1%29+=+x\"
\n" ); document.write( "simplify:
\n" ); document.write( "\"a%2Ax+-+a+=+x\"
\n" ); document.write( "add a to both sides of equation and subtract x from both sides of equation:
\n" ); document.write( "\"a%2Ax+-+x+=+a\"
\n" ); document.write( "factor out the x:
\n" ); document.write( "\"x%2A%28a-1%29+=+a\"
\n" ); document.write( "divide both sides by (a-1)
\n" ); document.write( "\"x+=+a%2F%28a-1%29\"
\n" ); document.write( "replace a with .69497895 and solve\"
\n" ); document.write( "\"x+=+.69497895%2F%281-.69497895%29\"
\n" ); document.write( "\"x+=+.69497895%2F-.30502105\"
\n" ); document.write( "\"x=+-2.278462259\"
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\n" ); document.write( "plug that value of x into your original equation:
\n" ); document.write( "\"2.79%5E%28x-1%29+-+4.377%5Ex+=+0\"
\n" ); document.write( "becomes:
\n" ); document.write( "\"2.79%5E%28-3.278462259%29+-+4.377%5E%28-2.278462259%29+=+0\"
\n" ); document.write( "you will find the answer to be 0 proving the value of x is correct.
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\n" ); document.write( "i may have messed up the digits but the real values were stored in the calculator and are accurate.
\n" ); document.write( "the values should be:
\n" ); document.write( ".69497895 for a
\n" ); document.write( "-.30502105 for 1-a
\n" ); document.write( "-2.278462259 for x
\n" ); document.write( "any deviation from these numbers above is a typo.
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\n" ); document.write( "there might be an easier way to do this but i don't see it right now.\r
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