9.
Determine whether each equation models a linear or non-linear relation.
a) $h=3 t$
b) $T=d^{2}$
c) $A=2^{i}$
d) $y=5-2 x$
e) $C=\frac{2}{3} n+8$

Step 1 ：\(h=3t\) can be written in the form \(y = mx + b\), with \(m = 3\) and \(b = 0\). Therefore, it is a linear relation.

Step 2 ：\(T=d^{2}\) cannot be written in the form \(y = mx + b\), as the variable \(d\) is squared. Therefore, it is a non-linear relation.

Step 3 ：\(A=2^{i}\) cannot be written in the form \(y = mx + b\), as the variable \(i\) is in the exponent. Therefore, it is a non-linear relation.

Step 4 ：\(y=5-2x\) can be written in the form \(y = mx + b\), with \(m = -2\) and \(b = 5\). Therefore, it is a linear relation.

Step 5 ：\(C=\frac{2}{3}n+8\) can be written in the form \(y = mx + b\), with \(m = \frac{2}{3}\) and \(b = 8\). Therefore, it is a linear relation.

Step 6 ：\(\boxed{\text{a) Linear, b) Non-linear, c) Non-linear, d) Linear, e) Linear}}\)