Problem: The formula expressing the relationship between x and y in the table is:
xyβ20β32β46β512β620ββ
Answer Choices:
A. y=2xβ4
B. y=x2β3x+2
C. y=x3β3x2+2x
D. y=x2β4x
E. y=x2β4
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.