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Determine if the sequence is arithmetic. If it is, find the common difference, the 52nd term, and the explicit formula.

34. -11, -7, -3, 1, . . .

Given the explicit formula for an arithmetic sequence find the common difference and the 52nd term.

35. a_n = -30 - 4n

Respuesta :

Answer:

  • #34. aₙ = 4n - 15; a₅₂ = 193
  • #35. a₅₂ = -238; d = - 4

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Question 34

Find the differences in the sequence  -11, -7, -3, 1, ...

  • 1 - (-3) = 4,
  • -3 - (-7) = 4,
  • -7 - (-11) = 4

The difference is common, so the sequence is an AP.

The nth term is:

  • [tex]a_n=a_1+(n-1)d[/tex]
  • [tex]a_n=-11+(n-1)*4=-11+4n-4=4n-15[/tex]

Find the 52nd term:

  • [tex]a_{52}=4*52-15=208-15=193[/tex]

Question 35

Find the 52nd term using the given formula:

  • [tex]a_{52}=-30-4*52=-30-208=-238[/tex]

Find the previous term:

  • [tex]a_{51}=-30-4*51=-30-204=-234[/tex]

Find the common difference:

  • [tex]d=a_{52}-a_{51}=-238-(-234)=-4[/tex]

Answer:

[tex]\begin{aligned}\textsf{34)} \quad d&=4\\a_n&=4n-15\\a_{52}&=193\end{aligned}[/tex]

[tex]\begin{aligned}\textsf{35)} \quad d&=-4\\a_{52}&=-238\end{aligned}[/tex]

Step-by-step explanation:

Question 34

An arithmetic sequence is a sequence of numbers in which the difference between consecutive terms is constant.

Given sequence:

  • -11, -7, -3, 1, ...

To determine if the given sequence is arithmetic, calculate the differences between consecutive terms.

[tex]a_4-a_3=1-(-3)=4[/tex]

[tex]a_3-a_2=-3-(-7)=4[/tex]

[tex]a_2-a_1=-7-(-11)=4[/tex]

As the differences are constant, the sequence is arithmetic, with common difference, d = 4.

The explicit formula for an arithmetic sequence is:

[tex]\boxed{a_n=a+(n-1)d}[/tex]

where:

  • a is the first term of the sequence.
  • n is the position of the term
  • d is the common difference between consecutive terms.

To find the explicit formula for the given sequence, substitute a = -11 and d = 4 into the formula:

[tex]\begin{aligned}a_n&=-11+(n-1)4\\&=-11+4n-4\\&=4n-15\end{aligned}[/tex]

To find the 52nd term, simply substitute n = 52 into the formula:

[tex]\begin{aligned}a_{52}&=4(52)-15\\&=208-15\\&=193\end{aligned}[/tex]

Therefore, the 52nd term is a₅₂ = 193.

[tex]\hrulefill[/tex]

Question 35

Given explicit formula for an arithmetic sequence:

[tex]a_n=-30-4n[/tex]

To find the common difference, we need to compare it with the explicit formula for the nth term:

[tex]\begin{aligned}a_n&=a+(n-1)d\\&=a+dn-d\\&=a-d+dn\end{aligned}[/tex]

The coefficient of the n-term is -4, therefore, the common difference is d = -4.

To find the 52nd term, simply substitute n = 52 into the formula:

[tex]\begin{aligned}a_{52}&=-30-4(52)\\&=-30-208\\&=-238\end{aligned}[/tex]

Therefore, the 52nd term is a₅₂ = -238.

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