Which statements are true about the graph of the function f(x) = x2 – 8x + 5? Check all that apply.

The function in vertex form is f(x) = (x – 4)2 – 11.
The vertex of the function is (–8, 5).
The axis of symmetry is x = 5.
The y-intercept of the function is (0, 5).
The function crosses the x-axis twice.

Question

Which statements are true about the graph of the function f(x) = x2 – 8x + 5? Check all that apply.

The function in vertex form is f(x) = (x – 4)2 – 11.
The vertex of the function is (–8, 5).
The axis of symmetry is x = 5.
The y-intercept of the function is (0, 5).
The function crosses the x-axis twice.

pandalover1999 · Answer

@mathmale

mathmale · Answer

Rewrite f(x) = x2 – 8x + 5    as      f(x) = x^2 – 8x + 5.  Have to show that exponentiation properly.

Since this question asks about "vertex form," you'll have to convert this equation to that form as we did earlier.

Take half of the coefff of x and square your result.  
Re-write f(x) = x2 – 8x + 5:  Between the -8x and the +5, add, and then subtract, the square of half of the coefficient of b (you have already done this).

mathmale · Answer

Your result?

jjcoolja12 · Answer

this can possibly help you in the future https://www.youtube.com/watch?v=3a7UbMJpeIM

mathmale · Answer

Half of -8 is what?:

Square this result.  Add, and then subtract, this result to your function.  Try it.  I'll help you if the results don't make sense to you.