Question

Answer the questions about the following function.
f(x)=2x^2-x-1
(a) Is the point (2,25) on the graph of f?
(b) If x =-2, what is f(x)? What point on the graph of f?
(c) If f(x)=-1, what is x? What point(s) are on the graph of f?
(d) What is the domain of f?
(e) List the x-intercept(s), if any, of the graph of f.
(f) List the y-intercept, if any, of the graph of f.

Answer 1

did you find \(f(2)\)?

Answer 2

What do you mean

Answer 3

\[f(x)=2x^2-x-2\] if \((2,25)\) is on the graph, that means \(f(2)=25\) so you have to find
\[f(2)=2\times 2^2-2-2\]

Answer 4

if you get 25, the answer is "yes" and if you do not, the answer is "no"

Answer 5

the answer was yes

Answer 6

seems unlikely

Answer 7

My math is all through a website from pearson

Answer 8

that may be, but
\[f(2)=2\times 2^2-2-2=8-2-2=6-2=4\] and not \(25\)

Answer 9

this system is a bit messed up and this is only my 3rd week in the class. I was doing good the 1st couple weeks now its getting a bit beyond what i know

Answer 10

are you sure it is
\[f(x)=2x^2-x-2\]?

Answer 11

For part A the answer was yes

Answer 12

NOw it wants to know If x=-2, what is f(x)?

Answer 13

no, for part A the answer is NO

Answer 14

\(f(2)=4\) not \(25\)

Answer 15

it said it was right

Answer 16

it isn't

Answer 17

Is the point (2,5) on the graph and i marked yes and it was right

Answer 18

ooh i thought you wrote \((2,25)\)

Answer 19

oh no it's ok though.
Now I am on part B

Answer 20

\[f(x)=2x^2-x-1\]
\[f(-2)=2\times (-2)^2-(-2)-1\]

Answer 21

you get
\[2\times 4+2-1=8+2-1=10-1=9\]

Answer 22

Part B says: If x=-2, what is f(x)?
f(-2)=

Answer 23

right, the answer is above

Answer 24

so put all of this
2×4+2−1=8+2−1=10−1=9

Answer 25

no you can just put in 9

Answer 26

Using this information, list a point on the graph of f.
(simplify your answer. Type and ordered pair, using integers or fractions.)

Answer 27

since \(f(-2)=9\) a point on the graph is \((-2,9)\)

Answer 28

Part C
If f(x)=-1, what is x?

Answer 29

you have to solve
\[2x^2-x-1=-1\] do you know how to do that?

Answer 30

no

Answer 31

add one to both sides and get
\[2x^2-x=0\] then factor

Answer 32

1/2

Answer 33

also \(0\) there are two solutions

Answer 34

so (1/2,0)

Answer 35

the two solutions are \(x=0\) and \(x=\frac{1}{2}\)

Answer 36

is that how i would type it in

Answer 37

it is not an ordered pair, i have no idea what pearson wants you to write

Answer 38

ahh
the 'points on the graph" are \((0,-1)\) and \((\frac{1}{2},-1)\)

Answer 39

ok
what is the domain of f

Answer 40

type it interval notation

Answer 41

I can't figure the domain out