document.write( "Question 143984: Thank you so much for your help! Can you please help me solve the equation....\r
\n" ); document.write( "\n" ); document.write( "42x + 4x+1 – 6 = 0\r
\n" ); document.write( "\n" ); document.write( "(the exponents are the 2x and x+1)
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Algebra.Com's Answer #104812 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
\"4%5E%282x%29%2B4%5E%28x%2B1%29-6=0\" Start with the given equation\r
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\n" ); document.write( "\n" ); document.write( "\"4%5E%282x%29%2B4%5E%28x%29%2A4%5E%281%29-6=0\" Rewrite \"4%5E%28x%2B1%29\" as \"4%5E%28x%29%2A4%5E%281%29\" using the identity \"x%5E%28y%2Bz%29=x%5E%28y%29%2Ax%5E%28z%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"4%5E%282x%29%2B4%5E%28x%29%2A4-6=0\" Evaluate \"4%5E1\" to get 4\r
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\n" ); document.write( "\n" ); document.write( "\"4%5E%282x%29%2B4%2A4%5E%28x%29-6=0\" Rearrange the terms\r
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\n" ); document.write( "\n" ); document.write( "\"%284%5E%28x%29%29%5E2%2B4%2A4%5E%28x%29-6=0\" Rewrite \"4%5E%282x%29\" as \"%284%5E%28x%29%29%5E2\" using the identity \"x%5E%28y%2Az%29=%28x%5E%28y%29%29%5Ez\"\r
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\n" ); document.write( "\n" ); document.write( "Let \"u=4%5Ex\"\r
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\n" ); document.write( "\n" ); document.write( "\"u%5E2%2B4%2Au-6=0\" Plug in \"u=4%5Ex\". In other words, replace each instance of \"4%5Ex\" with \"u\"\r
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\n" ); document.write( "\n" ); document.write( "Let's use the quadratic formula to solve for \"u\":\r
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\n" ); document.write( "\n" ); document.write( "Starting with the general quadratic\r
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\n" ); document.write( "\n" ); document.write( "\"au%5E2%2Bbu%2Bc=0\"\r
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\n" ); document.write( "\n" ); document.write( "the general solution using the quadratic equation is:\r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29\"\r
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\n" ); document.write( "\n" ); document.write( "So lets solve \"u%5E2%2B4%2Au-6=0\" ( notice \"a=1\", \"b=4\", and \"c=-6\")\r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-4+%2B-+sqrt%28+%284%29%5E2-4%2A1%2A-6+%29%29%2F%282%2A1%29\" Plug in a=1, b=4, and c=-6\r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-4+%2B-+sqrt%28+16-4%2A1%2A-6+%29%29%2F%282%2A1%29\" Square 4 to get 16 \r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-4+%2B-+sqrt%28+16%2B24+%29%29%2F%282%2A1%29\" Multiply \"-4%2A-6%2A1\" to get \"24\"\r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-4+%2B-+sqrt%28+40+%29%29%2F%282%2A1%29\" Combine like terms in the radicand (everything under the square root)\r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-4+%2B-+2%2Asqrt%2810%29%29%2F%282%2A1%29\" Simplify the square root (note: If you need help with simplifying the square root, check out this solver)\r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-4+%2B-+2%2Asqrt%2810%29%29%2F2\" Multiply 2 and 1 to get 2\r
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\n" ); document.write( "\n" ); document.write( "So now the expression breaks down into two parts\r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-4+%2B+2%2Asqrt%2810%29%29%2F2\" or \"u+=+%28-4+-+2%2Asqrt%2810%29%29%2F2\"\r
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\n" ); document.write( "\n" ); document.write( "Now break up the fraction\r
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\n" ); document.write( "\n" ); document.write( "\"u=-4%2F2%2B2%2Asqrt%2810%29%2F2\" or \"u=-4%2F2-2%2Asqrt%2810%29%2F2\"\r
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\n" ); document.write( "\n" ); document.write( "\"u=-2%2Bsqrt%2810%29\" or \"u=-2-sqrt%2810%29\"\r
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\n" ); document.write( "\n" ); document.write( "Remember, we let \"u=4%5Ex\". So \r
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\n" ); document.write( "\n" ); document.write( "\"4%5Ex=-2%2Bsqrt%2810%29\" or \"4%5Ex=-2-sqrt%2810%29\"\r
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\n" ); document.write( "\n" ); document.write( "Let's solve the first equation \"4%5Ex=-2%2Bsqrt%2810%29\" \r
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\n" ); document.write( "\n" ); document.write( "\"4%5Ex=-2%2Bsqrt%2810%29\" Start with the first equation\r
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\n" ); document.write( "\n" ); document.write( "\"log%2810%2C%284%5Ex%29%29=log%2810%2C%28-2%2Bsqrt%2810%29%29%29\" Take the log of both sides\r
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\n" ); document.write( "\n" ); document.write( "\"x%2Alog%2810%2C%284%29%29=log%2810%2C%28-2%2Bsqrt%2810%29%29%29\" Rewrite the left side using the identity \"log%28b%2C%28x%5Ey%29%29=y%2Alog%28b%2C%28x%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x=log%2810%2C%28-2%2Bsqrt%2810%29%29%29%2Flog%2810%2C%284%29%29\" Divide both sides by \"log%2810%2C%284%29%29\" to isolate x\r
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\n" ); document.write( "\n" ); document.write( "\"x=log%284%2C%28-2%2Bsqrt%2810%29%29%29\" Combine the logs by use of the change of base formula\r
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\n" ); document.write( "\n" ); document.write( "Now let's solve the second equation \"4%5Ex=-2-sqrt%2810%29\" \r
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\n" ); document.write( "\n" ); document.write( "\"4%5Ex=-2%2Bsqrt%2810%29\" Start with the first equation\r
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\n" ); document.write( "\n" ); document.write( "\"log%2810%2C%284%5Ex%29%29=log%2810%2C%28-2-sqrt%2810%29%29%29\" Take the log of both sides\r
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\n" ); document.write( "\n" ); document.write( "Notice how \"-2-sqrt%2810%29=-5.16228\". Since we cannot take the log of a negative number, this means we must ignore it.\r
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\n" ); document.write( "\n" ); document.write( "So the solution is \r
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\n" ); document.write( "\n" ); document.write( "\"x=log%284%2C%28-2%2Bsqrt%2810%29%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "which approximates to \r
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\n" ); document.write( "\n" ); document.write( "\"x=0.108477\"
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