# Fraction Problem

#### kuheli

##### New member
if b is the mean proportion between a and c ; prove that

(a^2 - b^2 + c^2) / (a^-2 - b^-2 + c^-2) = b^4

#### Petrus

##### Well-known member

if b is the mean proportion between a and c ; prove that

(a^2 - b^2 + c^2) / (a^-2 - b^-2 + c^-2) = b^4
Hello,
Do you got any progress?
do you know what they mean with "b is the mean proportion between a and c"
$$\displaystyle b^2=ac$$ put that on left side what do you got?

Regards,
$$\displaystyle |\pi\rangle$$

#### kuheli

##### New member
ya i got it .. thanks a lot