document.write( "Question 616469: help me solve this please: sqrt(x-3) = (no sqrt anymore) 6-x \n" ); document.write( "
Algebra.Com's Answer #387712 by jsmallt9(3758)![]() ![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "Since the square root is by itself already we can go ahead and square both sides: \n" ); document.write( " \n" ); document.write( "Squaring the square root is easy. Squaring the right side can easily be done incorrectly. You must use FOIL on (6-x)(6-x) or use the \n" ); document.write( " \n" ); document.write( "which simplifies to: \n" ); document.write( " \n" ); document.write( "Now we have an equation we can solve. It is a quadratic equation so we want one side to be zero. Subtracting x and adding 3 we get: \n" ); document.write( " \n" ); document.write( "Next we factor or use the Quadratic Formula. This won't factor so we have to use the formula: \n" ); document.write( " \n" ); document.write( "Simplifying... \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "So \n" ); document.write( "Since we squared both sides of the equation, which is not a mistake, we must check out solutions. Use the original equation: \n" ); document.write( " \n" ); document.write( "Checking \n" ); document.write( " \n" ); document.write( "Looking at the right side... \n" ); document.write( "Since the 6 = 12/2 and since the x value, (13 + sqrt(13))/2, is clearly more than 12/2, the right side turns out negative. The left side is a square root which cannot be negative. So this x value does not check and we reject it. (Note: this answer did not happen because we made a mistake. These \"non-solutiosn\" can happen any time you square both sides of an equation.) \n" ); document.write( "Checking \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "With the square root inside the square root, the rest of the check is bit of a mess. Before we square both sides, let's rewrite the right side as a binomial (so it will be easier to square): \n" ); document.write( " \n" ); document.write( "Squaring both sides: \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "Check! \n" ); document.write( "So the only solution to your equation is: \n" ); document.write( "P.S. Sorry about my earlier typo. I typed a -12 for the \"b\" instead of a -13. When I ended up with complex roots I should have thought to check my typing. \n" ); document.write( " |