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)![]() ![]() ![]() You can put this solution on YOUR website! As I understand your problem it is: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "Recognize that \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 \n" ); document.write( "becomes: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \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: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \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: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "Let's transpose sides, just to make this into a little more familiar form: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "Since both terms contain x, let's factor an x out and the problem becomes: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "Then notice that \n" ); document.write( "factoring form \n" ); document.write( "it factors to \n" ); document.write( "With that substitution the equation we have becomes: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \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: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "In summary, the three answers are x = 0, x = +1, and x = -1. \n" ); document.write( ". \n" ); document.write( "You can substitute these answers back into the original problem and see that they each \n" ); document.write( "work. \n" ); document.write( ". \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. \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( " |