PART 2

Topic: Arithmetic Sequence
Just find the value of the nth term
Note: some can't be solved by the arithmetic formula​

after solving finish this:
2. the 18th term of the sequence is ____
3. The 50th term of the sequence is ____
4.The 2023th term of the sequence is _____




pls ask if ur confused what to do, thanks

PART 2Topic Arithmetic SequenceJust find the value of the nth termNote some cant be solved by the arithmetic formulaafter solving finish this2 the 18th term of class=


Answer :

Answer:

[tex]Q 2: \quad a_{18} = -52[/tex]

[tex]Q3:\quad a_{50} = \dfrac{37}{3} = 12 \dfrac{1}{3}[/tex]

[tex]Q4:\quad a_{2023} = 4043[/tex]

Step-by-step explanation:

(I am not quite sure why you mentioned that some cannot be solved by the arithmetic sequence formula. Questions 2 - 4 are directly solvable by the arithmetic sequence formula)

First let's examine the sample problem and understand what the various terms mean

The formula for an arithmetic sequence is
[tex]a_n = a_1 + (n - 1)d\\\\$where\\a_n = $ nth term\\a_1 = $ first term\\n = number of terms\\d = common difference = difference between successive terms[/tex]

Question 2:
[tex]d = -5, a_1 = 33, n = 18[/tex]


[tex]a_{18} = 33+(18-1)(-5)\\\\a_{18} = 33 + (17)(-5)\\\\a_{18} = 33 - 85\\\\a_{18} = -52\\\\[/tex]

Question 3:

[tex]d = \dfrac{1}{3} - \dfrac{1}{12} = = \dfrac{4}{12} - \dfrac{1}{12} = \dfrac{3}{12} =\dfrac{1}{4}[/tex]
[tex]a_1 = \dfrac{1}{12}[/tex]

[tex]a_{50} = \dfrac{1}{12} + (50-1)\dfrac{1}{4}\\\\a_{50} = \dfrac{1}{12} + 49 \cdot \dfrac{1}{4}\\\\a_{50} = \dfrac{1}{12}+ \dfrac{49}{4}\\\\ a_{50} = \dfrac{1}{12}+ \dfrac{147}{12}\\\\ a_{50} = \dfrac{148}{12}\\\\ a_{50} = \dfrac{37}{3}\\\\a_{50} = 12 \dfrac{1}{3}[/tex]

Question 4

[tex]d = 3, a_1 = -2023, n = 2023[/tex]

[tex]a_{2023} = -2023 + (2023-1)(3)\\\\a_{2023} = -2023 + 2022 (3)\\\\a_{2023} = -2023 + 6066\\\\a_{2023} = 4043[/tex]

I hope that is what you were looking for

Answer:

[tex]\textsf{2.}\quad a_n=38-5n\: ; \quad a_{18}=-52[/tex]

[tex]\textsf{3.}\quad a_n=\dfrac{1}{4}n-\dfrac{1}{6}\: ; \quad a_{50}=\dfrac{37}{3}[/tex]

[tex]\textsf{4.}\quad a_n=3n-2026\: ; \quad a_{2023}=4043[/tex]  

Step-by-step explanation:

An arithmetic sequence is a sequence of numbers in which each term after the first is obtained by adding a common difference to the preceding term.

The general form of the nth term of an arithmetic sequence is:

[tex]\boxed{\begin{array}{l}\underline{\textsf{General form of the $n$th term of an arithmetic sequence}}\\\\a_n=a+(n-1)d\\\\\textsf{where:}\\\phantom{ww}\bullet\;\textsf{$a_n$ is the nth term.}\\ \phantom{ww}\bullet\;\textsf{$a$ is the first term.}\\\phantom{ww}\bullet\;\textsf{$d$ is the common difference between terms.}\\\phantom{ww}\bullet\;\textsf{$n$ is the position of the term.}\\\end{array}}[/tex]

[tex]\dotfill[/tex]

Question 2

Given arithmetic sequence:

[tex]33, \;28, \;23, \;18[/tex]

The first term is a = 33.

To find the common difference, subtract any term from the term that follows it. Let's subtract the second term from the third term:

[tex]d=23-28\\\\d=-5[/tex]

To write the nth term equation for the given arithmetic sequence, substitute the first term a = 33 and the common difference d = -5 into the general form:

[tex]a_n=33+(n-1)(-5)[/tex]

Simplify:

[tex]a_n=33-5n+5\\\\a_n=38-5n[/tex]

Therefore, the nth term equation of the given arithmetic sequence is:

[tex]\Large\boxed{\boxed{a_n=38-5n}}[/tex]

To find the 18th term, substitute n = 18 into the nth term equation:

[tex]a_{18}=38-5(18)\\\\a_{18}=38-90\\\\a_{18}=-52[/tex]

Therefore, the 18th term of the given arithmetic sequence is:

[tex]\Large\boxed{\boxed{a_{18}=-52}}[/tex]

[tex]\dotfill[/tex]

Question 3

Given arithmetic sequence:

[tex]\dfrac{1}{12},\;\dfrac{1}{3}, \;\dfrac{7}{12},\; \dfrac{5}{6}[/tex]

The first term is a = 1/12.

To find the common difference, subtract any term from the term that follows it. Let's subtract the first term from the second term:

[tex]d=\dfrac{1}{3}-\dfrac{1}{12} \\\\\\ d=\dfrac{1\cdot 4}{3\cdot 4}-\dfrac{1}{12} \\\\\\ d=\dfrac{4}{12}-\dfrac{1}{12} \\\\\\ d=\dfrac{4-1}{12} \\\\\\ d=\dfrac{3}{12} \\\\\\ d=\dfrac{3\div 3}{12\div 3} \\\\\\ d=\dfrac{1}{4}[/tex]

To write the nth term equation for the given arithmetic sequence, substitute the first term a = 1/12 and the common difference d = 1/4 into the general form:

[tex]a_n=\dfrac{1}{12}+(n-1)\dfrac{1}{4}[/tex]

Simplify:

[tex]a_n=\dfrac{1}{12}+\dfrac{1}{4}n-\dfrac{1}{4}\\\\\\a_n=\dfrac{1}{4}n+\dfrac{1}{12}-\dfrac{1\cdot 3}{4\cdot 3}\\\\\\ a_n=\dfrac{1}{4}n+\dfrac{1}{12}-\dfrac{3}{12}\\\\\\ a_n=\dfrac{1}{4}n+\dfrac{1-3}{12}\\\\\\ a_n=\dfrac{1}{4}n-\dfrac{2}{12}\\\\\\ a_n=\dfrac{1}{4}n-\dfrac{1}{6}[/tex]

Therefore, the nth term equation of the given arithmetic sequence is:

[tex]\Large\boxed{\boxed{a_n=\dfrac{1}{4}n-\dfrac{1}{6}}}[/tex]

To find the 50th term, substitute n = 50 into the nth term equation:

[tex]a_{50}=\dfrac{1}{4}(50)-\dfrac{1}{6}\\\\\\ a_{50}=\dfrac{25}{2}-\dfrac{1}{6}\\\\\\ a_{50}=\dfrac{25\cdot 3}{2\cdot 3}-\dfrac{1}{6}\\\\\\ a_{50}=\dfrac{75}{6}-\dfrac{1}{6}\\\\\\ a_{50}=\dfrac{75-1}{6}\\\\\\ a_{50}=\dfrac{74}{6}\\\\\\ a_{50}=\dfrac{37}{3}[/tex]

Therefore, the th term of the given arithmetic sequence is:

[tex]\Large\boxed{\boxed{a_{50}=\dfrac{37}{3}}}[/tex]

[tex]\dotfill[/tex]

Question 4

Given arithmetic sequence:

[tex]-2023, \; -2020,\;-2017[/tex]

The first term is a = -2023.

To find the common difference, subtract any term from the term that follows it. Let's subtract the first term from the second term:

[tex]d=-2020-(-2023)\\\\d=-2020+2023\\\\d=3[/tex]

To write the nth term equation for the given arithmetic sequence, substitute the first term a = -2023 and the common difference d = 3 into the general form:

[tex]a_n=-2023+(n-1)3[/tex]

Simplify:

[tex]a_n=-2023+3n-3\\\\a_n=3n-2026[/tex]

Therefore, the nth term equation of the given arithmetic sequence is:

[tex]\Large\boxed{\boxed{a_n=3n-2026}}[/tex]

To find the 2023rd term, substitute n = 2023 into the nth term equation:

[tex]a_{2023}=3(2023)-2026\\\\a_{2023}=6069-2026\\\\a_{2023}=4043[/tex]

Therefore, the 2023rd term of the given arithmetic sequence is:

[tex]\Large\boxed{\boxed{a_{2023}=4043}}[/tex]