document.write( "Question 101751This question is from textbook Precalculus with Limits
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\n" ); document.write( "\n" ); document.write( "(2z+3)^(2/3) + (2z+3)^(1/3) = 6\r
\n" ); document.write( "\n" ); document.write( "We've tried cubing each side which gets rather complicated, and we've tried factoring out a (2z+3)^(1/3), but we're not making any progress. Dad is helping, but he's having a tough time remembering complex radical problems!
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Algebra.Com's Answer #73988 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
\"root%283%2C%282z%2B3%29%5E2%29%2Broot%283%2C%282z%2B3%29%29=6\" Start with the given equation\r
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\n" ); document.write( "\n" ); document.write( "Let \"y=2z%2B3\"\r
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\n" ); document.write( "\n" ); document.write( "\"root%283%2Cy%5E2%29%2Broot%283%2Cy%29=6\" So now we get this equation in terms of y\r
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\n" ); document.write( "\n" ); document.write( "Here's an important side note: Take \"root%283%2Cy%5E2%29%2Broot%283%2Cy%29=6\" and subtract \"root%283%2Cy%29\" from both sides to get \"root%283%2Cy%5E2%29=6-root%283%2Cy%29\". This will be useful later\r
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\n" ); document.write( "\n" ); document.write( "Now let's move back to the main problem:\r
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\n" ); document.write( "\n" ); document.write( "\"root%283%2Cy%2Ay%29%2Broot%283%2Cy%29=6\" Factor \"y%5E2\"\r
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\n" ); document.write( "\n" ); document.write( "\"root%283%2Cy%29%2Aroot%283%2Cy%29%2Broot%283%2Cy%29=6\" Break down the root\r
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\n" ); document.write( "\n" ); document.write( "\"root%283%2Cy%29%28root%283%2Cy%29%2B1%29=6\" Factor out \"root%283%2Cy%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"%28root%283%2Cy%29%2B1%29=6%2Froot%283%2Cy%29\" Now divide both sides by \"root%283%2Cy%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"%28root%283%2Cy%29%2B1%29%5E3=%286%2Froot%283%2Cy%29%29%5E3\" Cube both sides\r
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\n" ); document.write( "\n" ); document.write( "\"y%2B3root%283%2Cy%29%2B3root%283%2Cy%5E2%29%2B1=216%2Fy\" Expand the left side\r
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\n" ); document.write( "\n" ); document.write( "Remember, \"root%283%2Cy%5E2%29=6-root%283%2Cy%29\", so replace \"root%283%2Cy%5E2%29\" with \"6-root%283%2Cy%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"y%2B3root%283%2Cy%29%2B3%2Ahighlight%28%286-root%283%2Cy%29%29%29%2B1=216%2Fy\" \r
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\n" ); document.write( "\n" ); document.write( "\"y%2B3root%283%2Cy%29%2B18-3root%283%2Cy%29%2B1=216%2Fy\" Distribute\r
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\n" ); document.write( "\n" ); document.write( "\"y%2B18%2Bcross%283root%283%2Cy%29-3root%283%2Cy%29%29%2B1=216%2Fy\" Notice the terms \"3root%283%2Cy%29\" and \"-3root%283%2Cy%29\" cancel to zero\r
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\n" ); document.write( "\n" ); document.write( "\"y%2B18%2B1=216%2Fy\" \r
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\n" ); document.write( "\n" ); document.write( "\"y%2B19=216%2Fy\" Combine like terms\r
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\n" ); document.write( "\n" ); document.write( "\"y%5E2%2B19y%5E2=216\" Multiply both sides by the LCD y to clear any fractions\r
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\n" ); document.write( "\n" ); document.write( "\"y%5E2%2B19y%5E2-216=0\" Get all terms to one side\r
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\n" ); document.write( "\n" ); document.write( "Now simply use any technique to solve for y\r
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\n" ); document.write( "\n" ); document.write( "When you solve for y (I simply used a calculator), you get \r
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\n" ); document.write( "\n" ); document.write( "\"y=8\" or \"y=-27\"\r
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\n" ); document.write( "\n" ); document.write( "Now plug in the first answer \"y=8\" into \"y=2z%2B3\"\r
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\n" ); document.write( "\n" ); document.write( "\"8=2z%2B3\"\r
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\n" ); document.write( "\n" ); document.write( "Now solve for z\r
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\n" ); document.write( "\n" ); document.write( "\"z=5%2F2\" which is \"z=2.5\"\r
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\n" ); document.write( "\n" ); document.write( "Now plug in the second answer \"y=-27\" into \"y=2z%2B3\"\r
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\n" ); document.write( "\n" ); document.write( "\"-27=2z%2B3\"\r
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\n" ); document.write( "\n" ); document.write( "Now solve for z\r
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\n" ); document.write( "\n" ); document.write( "\"z=-15\" \r
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\n" ); document.write( "\n" ); document.write( "Check:\r
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\n" ); document.write( "\n" ); document.write( "Let's check the answer \"z=5%2F2\"\r
\n" ); document.write( "\n" ); document.write( "\"root%283%2C%282z%2B3%29%5E2%29%2Broot%283%2C%282z%2B3%29%29=6\" Start with the given equation\r
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\n" ); document.write( "\n" ); document.write( "\"root%283%2C%282%285%2F2%29%2B3%29%5E2%29%2Broot%283%2C%282%285%2F2%29%2B3%29%29=6\" Plug in \"z=5%2F2\"\r
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\n" ); document.write( "\n" ); document.write( "\"root%283%2C%285%2B3%29%5E2%29%2Broot%283%2C%285%2B3%29%29=6\" Multiply 2 and \"5%2F2\" to get 5\r
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\n" ); document.write( "\n" ); document.write( "\"root%283%2C8%5E2%29%2Broot%283%2C8%29=6\" Add 5 and 3 to get 8\r
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\n" ); document.write( "\n" ); document.write( "\"root%283%2C64%29%2Broot%283%2C8%29=6\" Square 8 to get 64\r
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\n" ); document.write( "\n" ); document.write( "\"4%2B2=6\" Take the cube root of 64 to get 4 and take the cube root of 8 to get 2\r
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\n" ); document.write( "\n" ); document.write( "\"6=6\" Since the two sides of the equation are equal, this verifies our answer.\r
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\n" ); document.write( "\n" ); document.write( "Now let's check the answer \"z=-15\"\r
\n" ); document.write( "\n" ); document.write( "\"root%283%2C%282z%2B3%29%5E2%29%2Broot%283%2C%282z%2B3%29%29=6\" Start with the given equation\r
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\n" ); document.write( "\n" ); document.write( "\"root%283%2C%282%28-15%29%2B3%29%5E2%29%2Broot%283%2C%282%28-15%29%2B3%29%29=6\" Plug in \"z=-15\"\r
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\n" ); document.write( "\n" ); document.write( "\"root%283%2C%28-30%2B3%29%5E2%29%2Broot%283%2C%28-30%2B3%29%29=6\" Multiply 2 and \"-15\" to get -30\r
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\n" ); document.write( "\n" ); document.write( "\"root%283%2C%28-27%29%5E2%29%2Broot%283%2C-27%29=6\" Add -30 and 3 to get -27\r
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\n" ); document.write( "\n" ); document.write( "\"root%283%2C729%29%2Broot%283%2C-27%29=6\" Square -27 to get 729\r
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\n" ); document.write( "\n" ); document.write( "\"9-3=6\" Take the cube root of 729 to get 9 and take the cube root of -27 to get -3\r
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\n" ); document.write( "\n" ); document.write( "\"6=6\" Since the two sides of the equation are equal, this verifies our answer.\r
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