What is the inverse of 2x-8?

Answer 1

y = x² - 2x - 8

Swap x and y to find the inverse:

x = y² - 2y - 8

Now get y by itself:

y² - 2y = x + 8

(Complete the square):

y² - 2y + 1 = x + 9

(y - 1)² = x + 9

y - 1 = ±√(x + 9)

y = 1 ±√(x + 9)

Then there are two functions:

f(x) = 1 - √(x + 9)

and

f(x) = 1 + √(x + 9)

but an inverse can only be one function.

The functions above are a mirror image of the original function, but it is not an inverse (graph these functions).

There is no inverse.

Everything above is completely wrong. This is the inverse: (x+8)/2

I don't know where the x² came from in the first answer, but to work out the question as asked:

if y=2x-8

y+8 = 2x

(y+8)/2 = x

so, as the above answer stated, (x+8)/2 is the answer.