2.
Lee wants to find a formula for the nth term of this sequence.
He knows that it must be of the form an² + bn + c where a, b, and care constants.
So he puts
1,2,3 and makes Table 2, which he will match with Table 1 to find a, b and c.
E
Position
Sequence
1st differences
2nd differences
3. Explain why the 3rd term in Table 2 is 9a + 3b+c.
1 term
a+b+c
Table 2
3a+b
2nd term
4a+2b+c
3rd term