Question

Find the inverse of the function.
f(x) = 7x + 8
@satellite73 @jim_thompson5910 @zepdrix @dan815 @iambatman @thesmartone @perl @kainui

Answer 1

can you solve
\[7x+8=20\]?

Answer 2

Basic Idea:

1) replace f(x) with y

2) swap x and y

3) solve for y to get the inverse

------------------------------------------------------------------------

\[f(x) = 7x + 8\]
\[y = 7x + 8\]
\[x = 7y + 8\]
\[x-8 = 7y\]

what's the next step?

Answer 3

i have no clue what to do next @jim_thompson5910

Answer 4

7y means 7 times y

Answer 5

what is the complete opposite of multiplication?

Answer 6

division @jim_thompson5910

Answer 7

so you divide both sides by 7

Answer 8

Basic Idea:

1) replace f(x) with y

2) swap x and y

3) solve for y to get the inverse

------------------------------------------------------------------------

\[f(x) = 7x + 8\]
\[y = 7x + 8\]
\[x = 7y + 8\]
\[x-8 = 7y\]
\[\frac{x-8}{7} = y\]
\[y = \frac{x-8}{7}\]
\[f^{-1}(x) = \frac{x-8}{7}\]

Answer 9

ok so its y=8-x/7 @jim_thompson5910

Answer 10

is that the final answer @jim_thompson5910

Answer 11

yes what I got is the correct inverse

Answer 12

you can also state it as \[f^{-1}(x) = \frac{1}{7}x - \frac{8}{7}\]

Answer 13

thank u
can you help me with another one @jim_thompson5910

Answer 14

sure

Answer 15

Find the inverse of the function.
f(x) = 8x3 - 5
@jim_thompson5910

Answer 16

\[\Large f(x) = 8x^3 - 5\] right?

Answer 17

yes @jim_thompson5910

Answer 18

same idea as last time

1) replace f(x) with y

2) swap x and y

3) solve for y to get the inverse

show me how far you get when you follow these steps

Answer 19

y = 8x^3-5
8x^3=y-5
i dont know how to continue the rest @jim_thompson5910

Answer 20

you undo the -5 by adding 5 to both sides

Answer 21

try again

Answer 22

im so confused can you show me @jim_thompson5910