![]() I want to figure out, is this point right This is true, and you canĪdd 3 to both sides of this. And so this will be true ifĮither one of these is 0. X's will make this expression 0, and if they make Side, we still have that being equal to 0. On factoring quadratics if this is not so fresh- isĪ negative 3 and negative 1 seem to work. And whose sum is negativeĤ, which tells you well they both must be negative. Whose product is positive 3? The fact that their 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. (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. 3.He didn't exactly switch his x values to positive. Use your graphing calculator to solve Ex. Find how long it takes the ball to come back to the ground.Ģ2. The equation of the height of the ball with respect to time is \(y=-16 t^2+60 t\), where \(y\) is the height in feet and \(t\) is the time in seconds. Phillip throws a ball and it takes a parabolic path. How are the two equations related to each other?Ģ1. Graph the equations \(y=x^2-2 x+2\) and \(y=x^2-2 x+4\) on the same screen. What might be another equation with the same roots? Graph it and see.Ģ0. How are the two equations related to each other? (Hint: factor them.)Ĭ. What is the same about the graphs? What is different?ī. Graph the equations \(y=2 x^2-4 x+8\) and \(y=x^2-2 x+4\) on the same screen. Using your graphing calculator, find the roots and the vertex of each polynomial.ġ9. Whichever method you use, you should find that the vertex is at ( 10,−65).įind the solutions of the following equations by graphing.įind the roots of the following quadratic functions by graphing. The screen will show the x - and y-values of the vertex. Move the cursor close to the vertex and press. Move the cursor to the right of the vertex and press. Move the cursor to the left of the vertex and press. Use and use the option 'maximum' if the vertex is a maximum or 'minimum' if the vertex is a minimum. You can change the accuracy of the solution by setting the step size with the function. Use and scroll through the values until you find values the lowest or highest value of y. The approximate value of the roots will be shown on the screen. Use to scroll over the highest or lowest point on the graph. Whichever technique you use, you should get about x=1.9 and x=18 for the two roots. The screen will show the value of the root. Move the cursor close to the root and press. Move the cursor to the right of the same root and press. Move the cursor to the left of one of the roots and press Use and scroll through the values until you find values of y equal to zero. You can improve your estimate by zooming in. ![]() There are at least three ways to find the roots: ![]() For the graph shown here, the x-values should range from -10 to 30 and the y-values from -80 to 50. If this is not what you see, press the button to change the window size.
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