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)\"\" \"About 
You can put this solution on YOUR website!
\"sqrt%28x-3%29+=+6-x\"
\n" ); document.write( "Since the square root is by itself already we can go ahead and square both sides:
\n" ); document.write( "\"%28sqrt%28x-3%29%29%5E2+=+%286-x%29%5E2\"
\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 \"%28a-b%29%5E2+=+a%5E2-2ab%2Bb%5E3\" pattern. I like using the pattern:
\n" ); document.write( "\"x-3+=+%286%29%5E2-2%286%29%28x%29+%2B+%28x%29%5E2\"
\n" ); document.write( "which simplifies to:
\n" ); document.write( "\"x-3+=+x%5E2-12x+%2B+36\"
\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( "\"0+=+x%5E2+-13x+%2B+39\"

\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( "\"x+=+%28-%28-13%29+%2B-+sqrt%28%28-13%29%5E2+-4%281%29%2839%29%29%29%2F2%281%29\"
\n" ); document.write( "Simplifying...
\n" ); document.write( "\"x+=+%28-%28-13%29+%2B-+sqrt%28169+-4%281%29%2839%29%29%29%2F2%281%29\"
\n" ); document.write( "\"x+=+%28-%28-13%29+%2B-+sqrt%28169+-156%29%29%2F2%281%29\"
\n" ); document.write( "\"x+=+%28-%28-13%29+%2B-+sqrt%2813%29%29%2F2%281%29\"
\n" ); document.write( "\"x+=+%2813+%2B-+sqrt%2813%29%29%2F2\"

\n" ); document.write( "So \"x+=+%2813+%2B+sqrt%2813%29%29%2F2\" or \"x+=+%2813+-+sqrt%2813%29%29%2F2\"

\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( "\"sqrt%28x-3%29+=+6-x\"
\n" ); document.write( "Checking \"x+=+%2813+%2B+sqrt%2813%29%29%2F2\"
\n" ); document.write( "\"sqrt%28%28%2813+%2B+sqrt%2813%29%29%2F2%29-3%29+=+6-%28%2813+%2B+sqrt%2813%29%29%2F2%29\"
\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 \"x+=+%2813+-+sqrt%2813%29%29%2F2\"
\n" ); document.write( "\"sqrt%28%28%2813+-+sqrt%2813%29%29%2F2%29-3%29+=+6-%28%2813+-+sqrt%2813%29%29%2F2%29\"
\n" ); document.write( "\"sqrt%28%28%2813+-+sqrt%2813%29%29%2F2%29-6%2F2%29+=+12%2F2-%28%2813+-+sqrt%2813%29%29%2F2%29\"
\n" ); document.write( "\"sqrt%28%287+-+sqrt%2813%29%29%2F2%29+=+%28-1+%2B+sqrt%2813%29%29%2F2%29\"
\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( "\"sqrt%28%287+-+sqrt%2813%29%29%2F2%29+=+sqrt%2813%29%2F2+-+1%2F2%29\"
\n" ); document.write( "Squaring both sides:
\n" ); document.write( "\"%28sqrt%28%287+-+sqrt%2813%29%29%2F2%29%29%5E2+=+%28sqrt%2813%29%2F2+-+1%2F2%29%5E2%29\"
\n" ); document.write( "
\n" ); document.write( "\"7%2F2+-+sqrt%2813%29%2F2+=+13%2F4+-+sqrt%2813%29%2F2+%2B+1%2F4\"
\n" ); document.write( "\"7%2F2+-+sqrt%2813%29%2F2+=+14%2F4+-+sqrt%2813%29%2F2\"
\n" ); document.write( "\"7%2F2+-+sqrt%2813%29%2F2+=+7%2F2+-+sqrt%2813%29%2F2\"
\n" ); document.write( "Check!

\n" ); document.write( "So the only solution to your equation is: \"x+=+%2813+-+sqrt%2813%29%29%2F2\"

\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.
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