# Math (URGENT)

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How to graph:

y=x(x-4)

Calculator shows the vertex at (2,-4)
Can someone explain why? Thanks.

• Math (URGENT) -

Try completing the square.

x(x-4) = x^2 -4x +4 -4
= (x-2)^2 - 4

The vertex is the lowest point of the parabolic curve. That is obviously where x = 2, where the first term is zero.

The value of y there is -4.

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