The parabola y=ax2+bx+c is graphed below. Find a⋅b⋅c. (The grid lines are one unit apart.)
First, let's write this in vertex form.
We have y=a(x−h)2+k where (h,k) denotes the vertex. From the graph, we can write, y=a(x−3)2+1 since the vertex is at (3, 1)
Now, we have to find a. We can use the y intercept to help. We have
7=a(0−3)2+16=9aa=6/9=2/3
We find that when y=2/3(x−3)2+1, we have a y intercept at (0, 7), meaning we found our equation.
Now, we simply have to expand it. Expaning, we get y=23x2−4x+7.
This means abc=2/3(−4)7=−56/3
-56/3 is our answer!
Thanks! :)
We have the vertex form
y = a(x - h)^2 + k where the vertex (h,k) = (3,1)
We know that (0,7) is on the graph..so....
7 = a (0 - 3)^2 + 1
6 = 9a
a = 6/9 = 2/3
So
y = (2/3) ( x - 3)^2 + 1
y = (2/3) (x^2 - 6x + 9) + 1
y = (2/3)x^2 - 4x +6 + 1
y = (2/3)x^2 - 4x + 7
a*b*c = (2/3) (-4) (7) = -56 / 3