Question

Question #82350

Answer 1

Neither of you is correct. The real zeros of this polynomial are 1 and 4.

Explanation:

The easiest way to see this is by using the quadratic formula.
If you have a polynomial in the form of `ax + by + c`, then you can find both the real zeros like this:
1) `(-b-sqrt(b^2-4ac))/(2a)`

2) `(-b+sqrt(b^2-4ac))/(2a)`

In this case `a = -1`, `b = 5` and `c = -4`.
Plugging this in the formula you get:

1) `(-5-sqrt(5^2-4*(-1)*(-4))) / (2(-1)) = 4`

2) `(-5+sqrt(5^2-4*(-1)*(-4))) / (2(-1)) = 1`

So remember this formula:

`(-b+-sqrt(b^2-4ac))/(2a)`

Answer 2

There is no answer, where there is no question.

Explanation:

`-x^2+5x-4` is an expression, it is not a question.

If the question is: "Evaluate `-x^2+5x-4` when `x=1`, then your teacher is correct.

If the question is: "For what value of `x` does the expression evaluate to `-868`, then you are correct

If the question is something else, (Like where is the vertex of `y=-x^2+5x-4`) then it is possible that neither of you is correct.