Problem: The formula expressing the relationship between x and y in the table is:
xy​20​32​46​512​620​​
Answer Choices:
A. y=2x−4
B. y=x2−3x+2
C. y=x3−3x2+2x
D. y=x2−4x
E. y=x2−4
Solution:
Since the y-differences are 2,4,6,8, a quadratic function is suggested, thus eliminating (C). A quick check of the other choices shows that (B) is correct;
or
Make the check with each of the choices given.