Question

my last question to my test h.w
given that f(x) = 2x^2 - 3x + 4 and g (x) = 3x^2 + 4x - 5, find:
1. (f+g)(-2)
2. (f-g)(-3)
3. (f . g) (2/3)
4. (f/g) (- 4/5)
5. (f o g) (3)
6. (gof)(-4)
7.(f o f) ( 3/2)
8. ( g o g) (-1/2)

Answer 1

help functions discrete math

Answer 2

what is "test hw"?

Answer 3

home work test

Answer 4

in what part are you stumped on?

Answer 5

the prof did not teach this TT

Answer 6

some of my classmate and friends confused to

Answer 7

well; what does "(f+g)(-2)" mean? or rather, what do you understand this notation to mean?

Answer 8

function + ....

Answer 9

ok ... lets work with that

the notation is a shorthand for:

f(-2) + g(-2) ... but what do these notations signify?

Answer 10

they are the same

Answer 11

(f+g)(-2) means.. f(-2) + g(-2).

but what does f(-2) mean?

what does g(-2) mean?

notice the 2 functions have been named and defined as:

f(x) = 2x^2 - 3x + 4

and

g(x) = 3x^2 + 4x - 5

f(-2) is a way to say; what does f(x) = when x=-2

g(-2) is a way to say: what does g(x) = when x=-2

Answer 12

ic ic if im looking for X example sir (f+g) means x = (-2)

(f-g) x = (-3) correct or wrong?

Answer 13

if i read you correctly, then yes.

whatever is in the ()'s is the value they want you to use for "x" in the functions

Answer 14

the f+g part tells you want they want you to do with the functions; add them together in this case.

(f-g) subtract them

(f.g) = multiply them ..etc

Answer 15

f(-2) 2-2^2 - 3^2+ 4 g(-2) 3-2^2 + 4-2-5 sir?

Answer 16

the part that might be tricker is the (fog), (gog) and the like when there is the "o" in the middle

Answer 17

youve got it :)

Answer 18

after that sir what to do next?

Answer 19

(f+g)(-2) = f(-2): 2(-2)^2 -3(-2) +4 (+) g(-2): 3(-2)^2 +4(-2) -5

just add up all your values now to find (f+g)(-2)

Answer 20

sir 2(-2) =-4?

Answer 21

(f+g)(-2) =

f(-2): 2(-2)^2 -3(-2) +4
+ g(-2): 3(-2)^2 +4(-2) -5
------------------------
5(4) +1(-2) -1 = 20 -2-1 = 17 if i see it right

Answer 22

2(-2) = -4 yes

Answer 23

but; 2(-2)^2 = 2(4) = 8

Answer 24

i understand sir very well everything u tell your good 2x to my prof

Answer 25

thanx :)

the notation of (fog)(x) has a special meaning

it means that we use one function as the x value for the other function ... whcih can be tricky

Answer 26

we see that f(x) where x = -2 means f(-2)

but: f(g(x)) means that for every value of x in f(x) we use the value of g(x) at x=-2.

does that make sense?

Answer 27

i copy these before u go i have my test paper here need to send tommorow before prelim exam hahaha

Answer 28

sir 5(4) + 1 = 21 right then - 2 = 19? or wrong?

Answer 29

f(g(-2)) means we find g(-2) like normal:

g(-2) = 3(-2)^2 + 4(-2) - 5
= 3(4) + 4(-2) - 5
= 12 - 8 - 5
= 4 - 5
= -1

g(-2) = -1

f(g(-2)) means f(-1)

f(g(-2)) = 2(g(-2))^2 - 3(g(-2)) + 4
= 2(-1)^2 - 3(-1) + 4
= 2(1) + 3 + 4
= 2 + 7
= 9

all of these mean the same thing ...

(fog)(-2) = 9

f(g(x)) at x=-2; = 9

f(g(-2)) = 9

f(-1) = 9

Answer 30

5(4) + 1
20 + 1
21 ....... is correct

Answer 31

so no.1 question answer is 18 right or wrong?

Answer 32

but ,, that is not what its asking for :)

5 times (4) plus, 1 times (-2), minus 1 is how we read it

5 times (4) = 5(4) = 20

20 plus, 1 times (-2) = 20 + (-2) = 18

18 minus 1 = 18-1 = 17

Answer 33

so i get -1 from the last +4
-5
=-1
sir correct or wrong?