Chapter 4 - An Introduction to Functions - 4-3 Patterns and Nonlinear Functions - Practice and Problem-Solving Exercises - Page 250: 16

$y= 0.5x^2$

For the each y-coordinate{0, 0.5 , 2 , 4.5 , 8} , we could find they could all divide by 0.5 and later we could find this property of each ordered pairs . (0,0) $0=0.5\times0^2$ (1,0.5) $0.5=0.5\times1^2$ (2,2) $2= 0.5\times2^2$ ........ As a result, we could determine that the rule is $y= 0.5x^2$.