The inverse of f(x)= k(-x^3 -4x -9) is a function and f^-1(7)=1. What is the value of k?(adsbygoogle = window.adsbygoogle || []).push({});

Work is a picture: http://tinypic.com/view.php?pic=29xj4i8&s=5

Mod note: Too large picture deleted

Final Answer: k= (4y+10)/-7

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Algebra II Honors Homework Help

**Physics Forums | Science Articles, Homework Help, Discussion**