Question

Could someone please help me with this math question?

Which quadratic equation fits the data in the table?

A) y = x² − 7x − 1

B) y = −x² + 7x + 1

C) y = x² −7x + 1

D) y = x² + 7x + 1

Answer 1

Choice D works.

Explanation:

The table you have with `x` and `y` values should make the correct equation true. Remember the `x` and `y` values fit into each coordinate pair, or ordered pair, like this: `(x,y)`.
I looked first at the ordered pair `(0,1)`. If you put `0` in for `x` in equation A, you get `y=0^2-7(0)-1 = 0-0-1=-1`. But in the ordered pair `(0,1)`, `x=0` and `y=1`. When you plugged `0` in for `x`, you got `y=-1`, and that's not right.
Any of the others would give you `y=1` when you plug in `x=0`.
Another easy point to look at is `(1,9)`. Out of the next three choices, we want to see if we get `y=9` when we plug `1` in for `x`:

For B. we get: `-(1^2)+7(1)+1=-1+8+1=8`, and `8!=9`.

Equation C: `(1)^2-7(1)+1=-5`, and `-5!=9`.

Try D: `(1)^2+7(1)+1=9` and yes! `9=9`

So we don't need to try any other coordinate pairs; all of them should work, and these two don't work in equations A,B, or C.
I hope that helps!