SOLUTION: Find the vertex. y = x2 – 20x + 4

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Question 172428: Find the vertex. y = x2 – 20x + 4
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

In order to find the vertex, we first need to find the x-coordinate of the vertex.


To find the x-coordinate of the vertex, use this formula: x=%28-b%29%2F%282a%29.


x=%28-b%29%2F%282a%29 Start with the given formula.


From y=x%5E2-20x%2B4, we can see that a=1, b=-20, and c=4.


x=%28-%28-20%29%29%2F%282%281%29%29 Plug in a=1 and b=-20.


x=%2820%29%2F%282%281%29%29 Negate -20 to get 20.


x=%2820%29%2F%282%29 Multiply 2 and 1 to get 2.


x=10 Divide.


So the x-coordinate of the vertex is x=10. Note: this means that the axis of symmetry is also x=10.


Now that we know the x-coordinate of the vertex, we can use it to find the y-coordinate of the vertex.


y=x%5E2-20x%2B4 Start with the given equation.


y=%2810%29%5E2-20%2810%29%2B4 Plug in x=10.


y=100-20%2810%29%2B4 Square 10 to get 100.


y=100-200%2B4 Multiply -20 and 10 to get -200.


y=-96 Combine like terms.


So the y-coordinate of the vertex is y=-96.


So the vertex is .