The first four terms of an arithmetic sequence are given below.
Choose the algebraic expression that represents the nth
term in this sequence.
3, 6, 9, 12, . . .
3n
n - 3
3n - 3
n + 3
3n + 3
1
Right! The expression you selected, 3n, is correct.
The student got this item correct.
2
Sorry, the expression you selected, n - 3, is incorrect. The sequence in the question is: 3, 6, 9, 12,... But the expression you selected describes the sequence: -2, -1, 0, 1,...
The student did not get this item right.
3
Sorry, the expression you selected, 3n - 3, is incorrect. The sequence in the question is: 3, 6, 9, 12,... But the expression you selected describes the sequence: 0, 3, 6, 9,...
The student did not get this item right.
4
Sorry, the expression you selected, n + 3, is incorrect. You have found the correct recursive formula, but this is not the same as finding an expression for the nth term. The sequence in the question is: 3, 6, 9, 12,... and the expression you selected describes the sequence: 4, 5, 6, 7,...
The student did not get this item right.
5
Sorry, the expression you selected, 3n + 3, is incorrect. The sequence in the question is: 3, 6, 9, 12,... But the expression you selected describes the sequence: 6, 9, 12, 15,...
The student did not get this item right.
ExplicitArithmetic