Question

f(x)=3x-7 and g(x)=-2x-6. Find (f∘g)(4)
PLEASE SHOW ALL STEPS!

Answer 1

@nubeer

Answer 2

@phi

Answer 3

@ganeshie8

Answer 4

@dan815

Answer 5

@kropot72

Answer 6

(f∘g)(4)

means find g(4) by replacing x with 4 in the definition of g
then put that number into f(x)

Answer 7

I'm confused..

Answer 8

can you re-write
g(x)=-2x-6

by replacing x with 4 ?
what do you get ?

Answer 9

g(4)=-2(4)-6

Answer 10

yes, now do the arithmetic . can you simplify
-2(4)-6 ?

Answer 11

48?

Answer 12

-48*

Answer 13

-2*4 - 6

order of operations: multiply before add/subtract
-2*4 is -8
now do
-8 - 6= ?

Answer 14

-14.

Answer 15

when you get time, this video explains order of operations
http://www.khanacademy.org/math/arithmetic/multiplication-division/order_of_operations/v/introduction-to-order-of-operations

Answer 16

g(4)= -14

now do f( g(4) ) = f( -14)

Answer 17

uhhh hahaha whoa

Answer 18

replace x with -14 in
f(x)=3x-7

simplify (multiply before add)

Answer 19

f( g( 4)) is what (f∘g)(4) means.

you find what g(4) is, and then use that number in f

Answer 20

wait im confused. do i add 14 to both sides?

Answer 21

replace x with -14 in
f(x)=3x-7

same idea as for g(x): erase the x, put in a -14

Answer 22

and 3x is short for 3 * x (3 times x)

Answer 23

yes i have that. f(-14)=3(-14)-7

Answer 24

do i dont do anything with the f(-14) correct? just the other stuuff?

Answer 25

so -49 right? times 3*14 then subtract 7?

Answer 26

leave f(-14) like it is.

yes you get -49: 3* -14 then -7

Answer 27

okay :) so now what

Answer 28

that is the answer. But you have to show your work.

Answer 29

so thats just it? i wrote it all down but it looks incomplete :o why! haha. i hate math

Answer 30

I would say
(f∘g)(4) = f( g( 4))

then g(x)=-2x-6
g(4)= fill in your work
g(4)= -14

then f(x)= 3x-7
then replace x with g(4) (which you found is -14)
f(-14)= -49

Answer 31

okay cause mine doesn't look like that haha