document.write( "Question 83944: how do you solve quadratic equations and then also simplify the radical solution???\r
\n" ); document.write( "\n" ); document.write( "examle: 5(x.squared)- (x.squared)=42\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "help!!!
\n" ); document.write( "

Algebra.Com's Answer #60392 by bucky(2189)\"\" \"About 
You can put this solution on YOUR website!
Given:
\n" ); document.write( ".
\n" ); document.write( "\"5x%5E2+-+x%5E2+=+42\"
\n" ); document.write( ".
\n" ); document.write( "If you want, you can solve this without using the quadratic formula. Notice that the left
\n" ); document.write( "side of this equation simplifies to:
\n" ); document.write( ".
\n" ); document.write( "\"5x%5E2+-+x%5E2+=+4x%5E2\"
\n" ); document.write( ".
\n" ); document.write( "So you can substitute \"4x%5E2+\" for the left side of the equation you were given. This
\n" ); document.write( "makes the given equation become:
\n" ); document.write( ".
\n" ); document.write( "\"4x%5E2+=+42\"
\n" ); document.write( ".
\n" ); document.write( "Then you can find \"x%5E2\" by dividing both sides by 4 which is the multiplier of the
\n" ); document.write( "\"x%5E2\" term. This division of both sides by 4 reduces the equation to:
\n" ); document.write( ".
\n" ); document.write( "\"x%5E2+=+42%2F4\"
\n" ); document.write( ".
\n" ); document.write( "and \"42%2F4+=+10.5\"
\n" ); document.write( ".
\n" ); document.write( "Substituting \"10.5\" for \"42%2F4\" results in the equation becoming:
\n" ); document.write( ".
\n" ); document.write( "\"x%5E2+=+10.5\"
\n" ); document.write( ".
\n" ); document.write( "and taking the square root of both sides gives you the two answers:
\n" ); document.write( ".
\n" ); document.write( "\"x+=+sqrt%2810.5%29\" and \"x+=+-sqrt%2810.5%29\"
\n" ); document.write( ".
\n" ); document.write( "And since the square root of 10.5 is (from a calculator) 3.240370349, the two answers to
\n" ); document.write( "this problem are:
\n" ); document.write( ".
\n" ); document.write( "\"x+=+3.240370349\" and \"x+=+-3.240370349\"
\n" ); document.write( ".
\n" ); document.write( "But if you have to do the problem using the quadratic formula, you need to get the
\n" ); document.write( "original problem into the standard quadratic form of:
\n" ); document.write( ".
\n" ); document.write( "\"ax%5E2+%2B+bx+%2B+c+=+0\"
\n" ); document.write( ".
\n" ); document.write( "You still combine the two terms on the left side of the original equation to get:
\n" ); document.write( ".
\n" ); document.write( "\"4x%5E2+=+42\"
\n" ); document.write( ".
\n" ); document.write( "just as we did above. Next you need to get zero on the right side as the standard
\n" ); document.write( "quadratic form calls for. Do this by subtracting 42 from both sides of the equation.
\n" ); document.write( "That subtraction results in:
\n" ); document.write( ".
\n" ); document.write( "\"4x%5E2+-+42+=+0\"
\n" ); document.write( ".
\n" ); document.write( "This is in the standard quadratic form in which a = 4, b = 0 (because there is no term
\n" ); document.write( "that contains just x), and c = -42.
\n" ); document.write( ".
\n" ); document.write( "The quadratic formula says that the answer to the problem is determined by the equation:
\n" ); document.write( ".
\n" ); document.write( "\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"
\n" ); document.write( ".
\n" ); document.write( "Since b = 0 in this problem, the equation reduces to:
\n" ); document.write( ".
\n" ); document.write( "\"x+=+%280+%2B-+sqrt%28+0-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"
\n" ); document.write( ".
\n" ); document.write( "Next substitute 4 for a and -42 for c to get:
\n" ); document.write( ".
\n" ); document.write( "\"x+=+%280+%2B-+sqrt%28+0-4%2A4%2A%28-42%29+%29%29%2F%282%2A4%29+\"
\n" ); document.write( ".
\n" ); document.write( "The term in the radical [that is -4*4*(-42)] multiplies out to be 672 so the problem becomes:
\n" ); document.write( ".
\n" ); document.write( "\"x+=+%280+%2B-+sqrt%28+672+%29%29%2F%282%2A4%29+\"
\n" ); document.write( ".
\n" ); document.write( "The denominator of (2*4) becomes 8 which further simplifies the problem to:
\n" ); document.write( ".
\n" ); document.write( "\"x+=+%280+%2B-+sqrt%28672%29%29%2F8\"
\n" ); document.write( ".
\n" ); document.write( "Since the square root of 672 is (by a calculator) 25.92296279 the answers to this
\n" ); document.write( "problem become:
\n" ); document.write( ".
\n" ); document.write( "\"x+=+25.92296279%2F8\" and \"x+=+-25.92296279%2F8\"
\n" ); document.write( ".
\n" ); document.write( "When you do the division, the two answers are:
\n" ); document.write( ".
\n" ); document.write( "\"x+=+3.240370349\" and \"x+=+-3.240370349\"
\n" ); document.write( ".
\n" ); document.write( "And these are the same answers that we found earlier without using the quadratic formula.
\n" ); document.write( ".
\n" ); document.write( "Hope this discussion helps you to work your way through the problem.
\n" ); document.write( "
\n" );