Teacher2Teacher 
Q&A #202 
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From: Bobby Hostler <hostlerb@yahoo.com> To: Teacher2Teacher Public Discussion Date: 2007071611:38:04 Subject: Re: discriminants and roots? Why does a quadratic equation have one soution if the discriminant is zero. I don't know how to explain that. Ans: if the Discriminant is zero the function only crosses the x axis at one location therefore the discriminant is 1. easiest example would be y=x^2 versus y=x^29 on graphing calculator. What does a parabola with 2 xintercepts look like in equation form? Ans: there are many solutions to this question but the easiest is probably y=x^2b were b is constant. this will chose the vertex to move below the xaxis. again look at the examples above on your graphing calculator. For which value of k does kx2  10x + 25k = 0 1, 2, 3, 5 or 10? Ans: Use the discriminant to help you with this one. as long as the solution is a real number (not a complex number or b^24ac < 0) it will work. by the way this is asking you for what values of k does the graph cross the xaxis. so using an graphing calculator and substituting the numbers in for k may be easier.
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