s varies jointly as square of t and square of r, as s = 72 and t and r equals to 2 and 3 perspectively.
Let's find the value of the constant, k, of the given joint variation. We can use the formula s = kt²r² or simply, k = s/(t²r²).
[tex]\large \boxed{ \begin{array}{} \tt s =kt{}^{2}r {}^{2} \\ \tt 72= k(2) {}^{2} (3) {}^{2} \\ \tt 72 = (4)(9)k \\ \tt k = \frac{72}{36} \\ \tt k = 2 \end{array}}[/tex]
• Thus, the constant, k, of the given variation is 2.
