When we say that a quantity p varies jointly with r and s, we mean that there is a constant k such that:
p = krs
In this equation, p is the quantity that varies, and r and s are the variables that p depends on. The constant k represents the proportionality of how p changes with respect to r and s. To find the constant of variation k, you can rearrange the equation to isolate k:
k = ¼
Thus, the constant of variation k is expressed as:
k = ¼p / (rs)
This means that given the values of p, r, and s, you can determine k. The constant of variation is essential for understanding how changes in r and s influence the value of p.