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emilyliv emilyliv
wrote...
Posts: 154
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4 years ago
 QUESTION: Determine the vertex and the direction of opening for each quadratic function. Then state the number of zeros.
d) f(x) = 3(x +2)^2
I didn't understand the zeros part, the textbook said that there is 1 zero, but the zero is -2? The question was a little different, you didn't have to use the b^2 - 4ac formula.
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wrote...
Educator
4 years ago
Hi there, this is an incomplete quadratic, meaning that it doesn't have a constant at the end of it. To find the zeros, you could use the quadratic formula, but it's not required for incomplete quadratics. Just set f(x) = 0, like this:

\(f(x)=3(x+2)^2\)

\(0=3(x+2)^2\)

Divide both sides by 3:

\(\frac{0}{3}=\frac{3(x+2)^2}{3}\)

Simplifies to:

\(0=(x+2)^2\)

Now we square root both sides:

\(\sqrt{0}=\sqrt{(x+2)^2}\)

\(0=x+2\)

Solve for x:

\(x=-2\)

There is only one root.

If you'd like me to show you using the quadratic formula, let me know, reply back
emilyliv Author
wrote...
4 years ago
Thank you so much, but the thing that I don't get is how -2 is 1 root, shouldn't it be no roots because it is a negative?
wrote...
Educator
4 years ago
When you find -2 as a root, it means that you'll have a point along the x-axis that has the coordinates (-2, 0).

Here's what I mean looking at it graphically [see attachment]

I've also attached a video of how it's done for another example...
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emilyliv Author
wrote...
4 years ago
Thank you so much, I really appreciate it!
wrote...
Educator
4 years ago
Thank you so much, I really appreciate it!

Happy to help Perfect
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