Answer
$\displaystyle \frac{y_{2}}{y_{1}}$ and $\displaystyle \frac{y_{3}}{y_{2}} $ should be the same
Work Step by Step
An exponential curve is the graph of a function of the form
$y=f(x)=Ab^{x}$
The ratio $\displaystyle \frac{f(x+1)}{f(x)}=\frac{Ab^{x+1}}{Ab^{x}}=b$
tells us that
$\displaystyle \frac{y_{2}}{y_{1}}$ and $\displaystyle \frac{y_{3}}{y_{2}} $ should be the same in order for the points to lie on the curve.
