Check my answer quadratic function

[lizzpalmer]

Graph the following quadratic function and label its vertex. F(x) = 5x2 + 20x – 2

F(x) = 5x2+20x-2

Substitute -4, -2, 0, 2, 4 for x
(-4,-162)
(-2,-62)
(0,-2)
(2,58)
(4,158)

I think I might have something wrong because I thought the graph should look like a U

Let me know what you think!

 

[mmm4444bot]

F(x) = 5x^2 + 20x - 2

Lizz, remember that we text exponents using the caret symbol (shown in red above).


(-4,-162) Incorrect

(-2,-62) Incorrect

(0,-2) Correct

(2,58) Correct

(4,158) Correct

Please check your arithmetic. If you cannot locate the errors, please show your calculations.

Cheers

 

[lizzpalmer]

I did:

f(x) = 5(-4)^2 + 20(-4) - 2

= 5(-16) + -80 - 2

= -80 + -80 - 2

= -162

(-4, -162)

 

[JeffM]

I did:

f(x) = 5(-4)^2 + 20(-4) - 2

= 5(-16) + -80 - 2
Error is here. The product of two negative numbers is a positive number. So the square of a negative number is positive. (- 4)^2 = (-4) * (-4) = PLUS 16.

= -80 + -80 - 2

= -162

(-4, -162)

 

[lizzpalmer]

Thank you so much!!! I'm sure I did the same thing on the other part. I will redo it.