## katlin95 3 years ago Which of the following is the vertex of the function? y = x2 - 14x + 13 A. (1, 0) B. (3, -20) C. (5, -32) D. (7, -36)

1. MrYantho

You need to complete the square

2. MrYantho

Do you know how to do that?

3. katlin95

kinda

4. MrYantho

\[y=(x^2-14x)+14\] Then I take half the x coefficient and square it. Then I add and subtract that number \[y=(x^2-14x+49-49)+14\] Then I bring the minus number out of the brackets \[y=(x^2-14x+49)-49+14\] Now, what we have done is forced the brackets to be a perfect square. So we can factor \[y=(x-7)^2-49+14\] And just simplify \[y=(x-7)^2-35\] Now that it is in vertex form, we can see that the vertex is (7,-35)

5. MrYantho

Ok?

6. katlin95

wow yes!

7. MrYantho

Just remember...that in the step where we bring the negative 49 out of the brackets, if there is a number in front of the brackets, you would have had to multiply the -49 by that number when you bring it out.

8. katlin95

okay!:)

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