A sequence is defined by $$ x[k]=\frac{k^{2}}{2}+k, \quad k=0,1,2,3, \ldots $$ State the first five terms.

Short Answer

Expert verified
Answer: The first five terms of the given sequence are 0, \(\frac{3}{2}\), 4, \(\frac{15}{2}\), and 12.

Step by step solution

01

Understand the formula

We have a sequence defined by the following formula: $$ x[k]=\frac{k^{2}}{2}+k, \quad k=0,1,2,3, \ldots $$ We need to find the first five terms of this sequence by replacing k with consecutive natural numbers starting from 0.
02

Find the first term (k=0)

Plug in k = 0 into the formula: $$ x[0] = \frac{0^2}{2} + 0 = 0 $$ The first term of the sequence is 0.
03

Find the second term (k=1)

Plug in k = 1 into the formula: $$ x[1] = \frac{1^2}{2} + 1 = \frac{1}{2} + 1 = \frac{3}{2} $$ The second term of the sequence is \(\frac{3}{2}\).
04

Find the third term (k=2)

Plug in k = 2 into the formula: $$ x[2] = \frac{2^2}{2} + 2 = \frac{4}{2} + 2 = 2 + 2 = 4 $$ The third term of the sequence is 4.
05

Find the fourth term (k=3)

Plug in k = 3 into the formula: $$ x[3] = \frac{3^2}{2} + 3 = \frac{9}{2} + 3 = \frac{9}{2} + \frac{6}{2} = \frac{15}{2} $$ The fourth term of the sequence is \(\frac{15}{2}\).
06

Find the fifth term (k=4)

Plug in k = 4 into the formula: $$ x[4] = \frac{4^2}{2} + 4 = \frac{16}{2} + 4 = 8 + 4 = 12 $$ The fifth term of the sequence is 12. The first five terms of the given sequence are: 0, \(\frac{3}{2}\), 4, \(\frac{15}{2}\), and 12.

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