document.write( "Question 91637: a problem on a take home test cube root of 125-xcubed =5-x do i first cube both sides to get rid of the radical or should i solve the radical on the left side if i cube both sides i get 125- 5x to the 3 power. if take the cube root of the left side i get 5i times square root of 5 =5-x ihave no idea what to do please help thank you very much! \n" ); document.write( "
Algebra.Com's Answer #66555 by bucky(2189)\"\" \"About 
You can put this solution on YOUR website!
As I understand your problem it is:
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\n" ); document.write( "\"root%283%2C125%29-x%5E3+=+5+-+x\"
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\n" ); document.write( "Recognize that \"root%283%2C125%29\" is just a number that you can get on a calculator.
\n" ); document.write( "In this case, the answer can be done in your head. Ask yourself, \"What number multiplied
\n" ); document.write( "by itself three times results in 125?\" It can't be 4*4*4 because that results in 64. How
\n" ); document.write( "about 5*5*5. That answer is 125. (Note that -5*-5*-5 will not work because it results in
\n" ); document.write( "minus 125.) So you can replace \"root%283%2C125%29\" with 5. When you do that the problem
\n" ); document.write( "becomes:
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\n" ); document.write( "\"5+-+x%5E3+=+5+-+x\"
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\n" ); document.write( "Notice that you have 5 on both sides of the equation. You can get rid of them by subtracting
\n" ); document.write( "5 from both sides and the equation reduces to:
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\n" ); document.write( "\"-x%5E3+=+-x\"
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\n" ); document.write( "Next add x^3 to both sides of the equation. When you do the -x^3 on the left side disappears
\n" ); document.write( "and you are left with:
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\n" ); document.write( "\"0+=+x%5E3+-+x\"
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\n" ); document.write( "Let's transpose sides, just to make this into a little more familiar form:
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\n" ); document.write( "\"x%5E3+-+x+=+0\"
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\n" ); document.write( "Since both terms contain x, let's factor an x out and the problem becomes:
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\n" ); document.write( "\"x%28x%5E2+-1%29=+0\"
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\n" ); document.write( "Then notice that \"x%5E2+-+1\" is the difference between two squares. This is in the standard
\n" ); document.write( "factoring form \"a%5E2+-+b%5E2+=+%28a-b%29%2A%28a%2Bb%29\" Applying this rule to \"x%5E2+-1\" we find that
\n" ); document.write( "it factors to \"%28x-1%29%2A%28x%2B1%29\" and we can put this into the equation in place of \"x%5E2-1\".
\n" ); document.write( "With that substitution the equation we have becomes:
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\n" ); document.write( "\"x%28x-1%29%28x%2B1%29+=+0\"
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\n" ); document.write( "Notice that this equation will be true if any of the factors is equal to zero because
\n" ); document.write( "multiplying by a zero on the left side will result in the equation becoming 0 = 0. So
\n" ); document.write( "set each of the factors equal to zero and solve for x:
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\n" ); document.write( "\"x+=+0\" <=== that's one answer
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\n" ); document.write( "\"x+-+1+=+0+\" Solve by adding 1 to both sides to get \"x+=+1\" & that's another answer.
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\n" ); document.write( "\"x+%2B1+=+0+\" Solve by subtracting 1 from both sides to get \"x+=+-1\" & that's the last answer.
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\n" ); document.write( "In summary, the three answers are x = 0, x = +1, and x = -1.
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\n" ); document.write( "You can substitute these answers back into the original problem and see that they each
\n" ); document.write( "work.
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\n" ); document.write( "Hope this helps you to understand the problem. You didn't have to worry about the cube
\n" ); document.write( "root because in this case it was just the number 5. If the cube root had involved a
\n" ); document.write( "term containing x, that would have been a whole different problem.
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