document.write( "Question 535981: One solution of kx^2-5x+k=0 is 3. Find the other solution \n" ); document.write( "
Algebra.Com's Answer #352095 by bucky(2189)![]() ![]() ![]() You can put this solution on YOUR website! Problem: if one solution of the quadratic equation: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "is 3, what is the other solution? \n" ); document.write( ". \n" ); document.write( "Notice that when you term-by-term compare the given equation to the standard form of the quadratic equation: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "you can see that \"a\" correlates to k, \"b\" equals -5, and \"c\" also equals k. \n" ); document.write( ". \n" ); document.write( "We know that the quadratic formula applies to solving a quadratic equation in the standard form. The quadratic formula says that for a quadratic equation in the standard form x can be found from: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "into this formula we can substitute k for \"a\" and \"c\" and -5 for \"b\" to get: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "The \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "multiply both sides by 2*k which is the denominator on the right side. This clears the denominator, and the formula becomes: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "we also know that one value for x is 3. We were told that in the statement of the problem. So substitute 3 for x in the formula. This makes the left side become: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "multiply out the left side to get: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "get rid of the 5 on the right side by subtracting 5 from both sides: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "square both sides to get rid of the radical on the right side and this formula becomes: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "cancel 25 on both sides of the formula by subtracting 25 from both sides. Also get rid of the \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "Factor a k from terms on the left side: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "notice that this equation will be true if either of the two factors on the left side is equal to zero because multiplication by a zero results in the left side becoming zero and making the left side equal to the zero on the right side. \n" ); document.write( ". \n" ); document.write( "So this formula will be true if either k = 0 or if 40k - 60 = 0. We can ignore k = 0 because if this were true in the original quadratic equation of the problem if k were zero, both the \n" ); document.write( ". \n" ); document.write( "then dividing both sides by 60: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "and reducing the right side by dividing both the numerator and denominator by 20 to get: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "Now we can go back to the original problem and substitute \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "Multiply all terms by 2 to cancel out the denominator and you have: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "compared to the standard quadratic equation we now have \"a\" = 3, \"b\" = -10, and \"c\" = 3. Substituting these values into the quadratic formula, we get: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "which becomes: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "Simplifying to: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "The radical term becomes the square root of 64: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "which simplifies to: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "and \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "The first value for x we already knew because it was part of the problem. The second value for x, which we found was \n" ); document.write( ". \n" ); document.write( "Hope this helps you to understand the quadratic equation a little better and how to apply that knowledge to solving this problem. \n" ); document.write( ". \n" ); document.write( "Check my work. It's late and I might have introduced some errors due to lack of coffee. You can also check this problem by multiplying the two factors: \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "Good luck ... \n" ); document.write( ". \n" ); document.write( " \n" ); document.write( " |