Question

Let f(x)=-2x-9 with domain I. Find the following.
a.f(-7)
b.f(100)
c.f(-a)in terms of a

Answer 1

substitute each value seperately... x = -7, x = 100 then evaluate.

for x = -a just substitute and evaluate.... but you will still end up with an equation

Answer 2

not understanding, a? b? c?

Answer 3

ok...for the 1st part find

\[ f(-7) = -2 \times -7 - 9\]

you need to evaluate... get a number answer for this

Answer 4

Please help me, I am not understanding any of this

Answer 5

Ok, so I got 5 for the first, now the second?

Answer 6

ok... here it is again

\[f(-7) = ( - 2 \times -7) - 9\]

can you get a number answer for the right hand side of the equation...?

Answer 7

I got 5 for a, what about b and c??

Answer 8

ok... thats the 1st part...

repeat the above for x = 100

so in the above equation replace - 7 with 100

then for part c replace - 7 with - a

Answer 9

-209 for b

Answer 10

thats correct...

Answer 11

Ok so what is the anwer for c???

Answer 12

\[f(-a) = (-2 \times -a) - 9\]

simplify it... and it will be an equation

Answer 13

Is it -2x-a-9?

Answer 14

no remember yo are replacing x with -a

Answer 15

and in the equation I've written its a multiplication sign between -2 and -a

Answer 16

I don't know, I keep getting the anwswer wrong, I only have one more try to get the answer correct, please help me

Answer 17

what is -2 times -a ...?

Answer 18

2a?

Answer 19

right

Answer 20

ok, so what is the answer for c?

Answer 21

correct... so

f(-a) = 2a - 9

Answer 22

right

Answer 23

Ok, I got it!

Answer 24

hope it helps

Answer 25

Yes, thank you so much

Answer 26

I have one more problem

Answer 27

sorry... I have to go... but there are lots of people here who can help... good luck