What is the equation of the inverse of the function?

f(x)=3x8+1
options:

f−1(x)=83x−13

f−1(x)=83x−83

f−1(x)=83x−1

f−1(x)=38x−1

Solve this riddle: i am an odd number. i an less than 100. the some of my digit is 12. i am a multiple of 15. what number am i?

Using elimination, what is -4x+2y=-12 4x+8y=-24

Find the volume of the solid obtained by rotating the region enclosed by the curves y=1x and y=7^-x about the x-axis. (use symbolic notation and fractions where needed.) volume =