The value of f-1(8) is 3.
In order to find this, we first need to find the inverse function. Since f-1 means inverse function, it is the first thing to look for.
To find any inverse function, you need to switch the f(x) and x values and then solve for the new f(x).
f(x) = (5x + 1)/2 ----> Switch x and f(x)
x = (5f(x) + 1)/2 ----> Multiply both sides by 2
2x = 5f(x) + 1 ----> Subtract 1 from both sides
2x - 1 = 5f(x) -----> Divide by 5
f-1(x) = (2x - 1)/5
Now we can plug 8 in for the x in the new equation to find the value.
f-1(x) = (2x - 1)/5
f-1(8) = (2(8) - 1)/5
f-1(8) = (16 - 1)/5
f-1(8) = (15)/5
f-1(8) = 3
