Question

Given the function f(x)=4(x+3)-5, solve for the inverse function when x=3.

Answer 1

plz help

Answer 2

@Mehek14

Answer 3

@Michele_Laino

Answer 4

To find the inverse of a function, you always want to change x and y, then solve for y again.

First, change f(x) to y to avoid any confusion. \[y=4(x+3)-5\]

Now, swap x and y. \[x=4(y+3)-5\]

All you have to do now is solve for y. Once you've done that, substitute 3 in for x, and you'll be all set!

Answer 5

Wait so how do you substitute x for 3?

Answer 6

@adrianna45

Answer 7

@nincompoop can you please help?

Answer 8

@perl

Answer 9

by plug in x=3

Answer 10

Just replace x to 3.

Answer 11

so it would be x=4(y+3)-5
x=4(3+3)-5?

Answer 12

@geerky42

Answer 13

Are you still working on this ?

Answer 14

yes

Answer 15

f(x) = y = 4(x+3) - 5 is a line that is given

y = 4x + 12 -5
y = 4x + 7

Answer 16

ya so when do you substitute x for 3?

Answer 17

The inverse of that , will be another line that is reflected over the line with slope 1, y=x.

To figure that , you can just switch x and y around and resolve for the new y.

Answer 18

Original: y = 4x + 7

Inverse: x = 4y + 7
x - 7 = 4y
y = (x-7) / 4

Answer 19

Put x=3 in the inverse function, calculate the y value

Answer 20

-1?

Answer 21

That's correct.

Answer 22

See it is a reflection if you switch the x and y around, as in the graph

Answer 23

ya i see it. it really helped thank you so much and do you know how to do f(g(x) problems?

Answer 24

sure

Answer 25

well i need help with Given that f(x) = x2 + 2x + 3 and g(x) = quantity of x plus four, over three, solve for f(g(x)) when x = 2.

Answer 26

like i dont know how to setup

Answer 27

solve g(2) first, what is that

Answer 28

g(x) = (x+4) / 3

Answer 29

2?

Answer 30

wait do you put 2 for x?

Answer 31

yes, now find f[g(2)], what do ya think to do?

Answer 32

4x2x+3 than 6x=3 which is 2?

Answer 33

since g(2) = 2 , start from the middle and work outwards


f(2) = 2^2 + 2*2 + 3

Answer 34

11?

Answer 35

yeah

Answer 36

oh i forgot to substitute x with 2 for 2x

Answer 37

so if i haveanother problem like in future do i solve g first? or depending on the problem

Answer 38

for compound functions like f([g(x)] start with the inner function, evaluate if given a value, then use g(x) value in f(x)...

work inner function to outer functions

Answer 39

ohok thank you very much!

Answer 40

welcome, goodluck

Answer 41

there are like some problems like f(x) and g(x) and you have to compare them. there are lot of problems but i dont know how to compare like if you know how to do it i will put it on new page

Answer 42

sure, just tag my name with @name

Answer 43

ok thanks