Question

Help with quick question. Medal to best answer. Thanks!

f(x)=-2x-1 for all real numbers.
What is f^-1(x), the inverse of f(x)?

Answer 1

this link will give u the BEST ansewr http://www.webmath.com/nsolve.html

Answer 2

I did it and it wouldn't go through. it said something about an incorrect variable. What variable do I put in?

Answer 3

@campbell_st

Answer 4

both

Answer 5

ok... to find the inverse swap x and y

so

if y = -2x - 1

make the swap

x = -2y - 1

now to find the inverse, make y the subject of the equation.

Answer 6

subject meaning find y?

Answer 7

yes, get a single y equal to something...

Answer 8

so i plug in a number for y

Answer 9

or x

Answer 10

no.... making y the subject

add 1 to both sides of the equation.

then divide both sides of the equation by -2

Answer 11

so...adding 1 to both sides: 1x=-2y+0

Answer 12

then dividing by -2= ???

Answer 13

x = -2y - 1

***so...adding 1 to both sides: 1x=-2y+0****

to add, write +1 on both sides:
x+1 = -2y -1 + 1

you can simplify the right side (-1+1 is 0 and -2y + 0 is -2y)
you get
x+1 = -2y

now divide both sides by -2
(that means divide *everything* on the left side by -2

Answer 14

so 1/-2 = 0.5 so -2x+0.5 = -2y

Answer 15

@phi

Answer 16

the idea is you have an equation (two sides are equal)
you divide each side "in half" and they are still equal
to show "divide in half" we write /(-2) under the entire side.
we do that to both sides

can you do that for
x+1 = -2y

Answer 17

in other words draw a line under x+1, and then write -2 under the line
on the right side, draw a line under -2y, then write -2 under that line

can you do that ?

Answer 18

yes I did and i figured out the answer. THanks so much