00:01
I want to graph the quadratic function, f of x equals 2x squared, minus x, minus 3.
00:14
And when i start, i want to note that my c value here is my y intercept.
00:20
So i know that my y intercept is at negative 3.
00:23
And so the other two points that i want to find are my vertex and my roots.
00:30
So to find my vertex, we're going to use the vertex formula with the negative b over 2a.
00:41
And so a is going to be my lead coefficient, which is 2.
00:46
B is going to be the coefficient of my second term, in this case is negative 1.
00:50
And so i'm taking x equals negative b, so positive 1, divided by 2 times a, which is positive 2, that's going to give me one -fourth.
01:02
I'm going to put it as 0 .25 just because it's going to make calculations a little bit easier to find my y value.
01:09
To find my y, i'm going to evaluate f of 0 .25 for this function, so 2 times 0 .25 squared minus 0 .25 minus 3.
01:25
So all i did was plug that 0 .25 in for x.
01:29
And when i do that, that two times .25 squared is going to give me .125 minus .25, minus 3, giving me negative 3 .125.
01:44
So my vertex is going to be .25, comma, negative 3 .125.
01:53
So not the nicest number, but we are going to go ahead and plot that...