# Thread: [SOLVED] finding inverse formulas

1. ## [SOLVED] finding inverse formulas

i can find the inverse of a function, but im having trouble finding the formulas in these problems

Find a formula for the inverse of the function.
y = 8x^3 + 7

Find a formula for the inverse of the function. y = ln(x + 8)

2. Originally Posted by kyleu03
i can find the inverse of a function, but im having trouble finding the formulas in these problems

Thank you!

3. Originally Posted by kyleu03
i can find the inverse of a function, but im having trouble finding the formulas in these problems

Find a formula for the inverse of the function.
y = 8x^3 + 7

Find a formula for the inverse of the function. y = ln(x + 8)
Why don't you apply your knowledge to the first problem? It's not really any different.

$\displaystyle y = 8x^3+7 $$\displaystyle x = 8y^3+7 \displaystyle x-7 = 8y^3 Take the cube root. \displaystyle y = \sqrt[3]{\frac{(x-7)}{8} } 4. Originally Posted by A Beautiful Mind Why don't you apply your knowledge to the first problem? It's not really any different. \displaystyle y = 8x^3+7$$\displaystyle x = 8y^3+7$
$\displaystyle x-7 = 8y^3$

Take the cube root.

$\displaystyle y = \sqrt[3]{\frac{(x-7)}{2} }$

thats wrong...

5. Originally Posted by kyleu03
thats wrong...
the /2 should be /8

but thanks

6. still cant figure out
y = ln(x + 8)