Question

What is the answer to this question I am really having trouble ??

Answer 1

Answer: Choice B

y = x^2 + 7x + 1

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Proof:

A quick way to confirm that choice B is the only answer is to eliminate the other non-answers.

If you plugged x = 1 into the equation for choice A, you would get

y = -x^2 + 7x + 1

y = -1^2 + 7(1) + 1

y = -1 + 7 + 1

y = 7

We get a result of 7, but we want 9 to be the actual output. So choice A is out.

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Repeat for choice C. Plug in x = 1

y = x^2 - 7x + 1

y = 1^2 - 7(1) + 1

y = 1 - 7 + 1

y = -5

We can eliminate choice C (since again we want a result of y = 9)

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Finally let's check choice D

y = x^2 - 7x - 1

y = 1^2 - 7(1) - 1

y = 1 - 7 - 1

y= -7

so choice D is off the list as well

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The only thing left is choice B, so it must be the answer. It turns out that plugging x = 1 into this equation leads to y = 9 as shown below

y = x^2 + 7x + 1

y = 1^2 + 7(1) + 1

y = 1 + 7 + 1

y = 9

And the same applies to any other x value in the table (eg: plugging in x = 3 leads to y = 31, etc etc).