Hi, I can't figure out the inverse of f(x)=8x^3-6, can someone help me please?
Let's write
y = 8x^3 - 6 Let's get x by itself .... add 6 to both sides
y + 6 = 8x^3 Divide by 8 on both sides
(y + 6) / 8 = x ^3 Take the cube root of both sides.....
[(y + 6)/ 8]^(1/3) = x Now "swap" x and y
[(x + 6)/ 8]^(1/3) = y And, for y, write f -1(x) and there's the inverse
We can use an informal way to check that this is the inverse - it isn't foolproof, but it will work in most cases.....
Note that the inverse should "reverse" the x and y coordinates on a graph. So, in the original problem, let x = 1 and y will = 2. Then, in the inverse, let x =2, and we should get y =1...and we do!! So, we're pretty sure it's correct.......