## Precalculus (10th Edition)

linear $H(x)=2x+4$
The ratio of consecutive values is not constant (because $\frac{4}{2}\ne\frac{6}{4}$) hence, the function is not exponential. The difference of consecutive values is constant ($2$), hence the function is linear and the slope (the coefficient of $x$) is $2$. $H(0)=4$ so the $y$-intercept is $4$. Thus, the slope-intercept form of the function that models the data is $H(x)=2x+4.$