SOLUTION: Find y-intercept and vertex y = x^2 - 3x

SOLUTION: Find y-intercept and vertex y = x^2 - 3x - 4

Question 91110: Find y-intercept and vertex y = x^2 - 3x - 4
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
To find the y-intercept, plug in x=0

Lets find the value of y when

Start with the given polynomial

Plug in

Raise 0 to the second power to get 0

Multiply 3 by 0 to get 0

Remove any zero terms

So when ,

So the y-intercept is (0,-4)

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To determine the x-value of the vertex, use this formula

From the equation we can see that a=1 and b=-3

Plug in b=-3 and a=1

Negate -3 to get 3

Multiply 2 and 1 to get 2

Reduce

So the x-coordinate of the vertex is (which is in decimal form). Lets plug this into the equation to find the y-coordinate of the vertex.

Lets evaluate

Start with the given polynomial

Plug in

Raise 1.5 to the second power to get 2.25

Multiply -3 and 1.5 to get -4.5

Now combine like terms

So the vertex is (1.5,-6.25)

Here is a graph to see the vertex and y-intercept

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