And now we can attempt toįactor this left-hand side. Plus 15 over 5 is 3 isĮqual to 0 over 5 is just 0. Me- these cancel out and I'm left with x squared The x squared term that's not a 1, is to see if I canĭivide everything by that term to try to simplify I like to do whenever I see a coefficient out here on We're going to try to solve the equation 5x Those three points then I should be all set with And then I also want toįigure out the point exactly in between, which is the vertex. Minus 20x plus 15, when does this equal 0? So I want to figure Seen, intersecting the x-axis is the same thingĪs saying when it does this when does y equal I want to first figure out whereĭoes this parabola intersect the x-axis. You can just take threeĬorresponding values for y are and just graph The following equation y equals 5x squared Therefore, 3 and 1 are the only possible x values. So -3 doesn't work as an x, and the same thing would happen with -1:īoth of these solved binomial equations show that -3 and -1 cannot be x values for the parabola. X cannot equal -3 or -1 because if x was -3 then this would happen: The reason that Sal made the x values positive 3 and 1 is because they are the only two x values that would make his equation equal zero.
CONVERTING QUADRATIC TO STANDARD CALCULATOR HOW TO
(this basically explains how to get the 3 and 1 for the x values and it explains why -3 and -1 do not work for x values.) I think that was the question you were asking, I hope that helped, if not, hopefully this will: you can check them out if you are still confused. The -3 and -1 were not x values, they were just what he used to factor in a way that he teaches in previous factoring videos. In order to find the x values he used that binomial and made it equal 0, and his x values that he found were 3 and 1.
the -3 and -1 were numbers that he got when he factored the equation into a binomial. the -3 and the -1 that he got were not his x values.
He didn't exactly switch his x values to positive.
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