Evaluate variable expressions for number sequences
Learn with an example
📢 Find the first four terms of the sequence defined below, where n represents the position of a term in the sequence. Start with n = 1.
– 9n + 4
____ ,___ ,___ , _____
To find the 1st term, plug in n = 1.
-9n + 4 = -9(1) + 4 = -9 + 4 = -5
To find the 2nd term, plug in n = 2.
– 9n + 4 = – 9(2) + 4 = -18 + 4 = -14
To find the 3rd term, plug in n = 3.
-9n + 4 = -9(3) + 4 = -27 + 4 = -23
To find the 4th term, plug in n = 4.
– 9n + 4 = – 9(4) + 4 = -36 + 4 = -32
The first four terms of the sequence are -5, -14, -23, -32.
📢 Find the first four terms of the sequence defined below, where n represents the position of a term in the sequence. Start with n = 1.
3(4)n
____ ,___ ,___ , _____
To find the 1st term, plug in n = 1.
3(4)n = 3(4)1 = 3(4) = 12
To find the 2nd term, plug in n = 2.
3(4)n = 3(4)2 = 3(16) = 48
To find the 3rd term, plug in n = 3.
3(4)n = 3(4)3 = 3(64) = 192
To find the 4th term, plug in n = 4.
3(4)n = 3(4)4 = 3(256) = 768
The first four terms of the sequence are 12, 48, 192, 768.
📢 Find the first four terms of the sequence defined below, where n represents the position of a term in the sequence. Start with n = 1.
–6n − 1
___ ,____ ,____ ,___
To find the 1st term, plug in n = 1.
-6n − 1 = -6(1) − 1 = -6 − 1 = -7
To find the 2nd term, plug in n = 2.
-6n − 1 = -6(2) − 1 = -12 − 1 = -13
To find the 3rd term, plug in n = 3.
-6n − 1 = -6(3) − 1 = -18 − 1 = -19
To find the 4th term, plug in n = 4.
-6n − 1 = -6(4) − 1 = -24 − 1 = -25
The first four terms of the sequence are -7, -13, -19, -25.
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