# 11.2 Arithmetic sequences  (Page 5/8)

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What are the main differences between using a recursive formula and using an explicit formula to describe an arithmetic sequence?

Describe how linear functions and arithmetic sequences are similar. How are they different?

Both arithmetic sequences and linear functions have a constant rate of change. They are different because their domains are not the same; linear functions are defined for all real numbers, and arithmetic sequences are defined for natural numbers or a subset of the natural numbers.

## Algebraic

For the following exercises, find the common difference for the arithmetic sequence provided.

$\left\{5,11,17,23,29,...\right\}$

$\left\{0,\frac{1}{2},1,\frac{3}{2},2,...\right\}$

The common difference is $\frac{1}{2}$

For the following exercises, determine whether the sequence is arithmetic. If so find the common difference.

$\left\{11.4,9.3,7.2,5.1,3,...\right\}$

$\left\{4,16,64,256,1024,...\right\}$

The sequence is not arithmetic because $16-4\ne 64-16.$

For the following exercises, write the first five terms of the arithmetic sequence given the first term and common difference.

${a}_{1}=-25$ , $d=-9$

${a}_{1}=0$ , $d=\frac{2}{3}$

$0,\text{\hspace{0.17em}}\frac{2}{3},\text{\hspace{0.17em}}\frac{4}{3},\text{\hspace{0.17em}}2,\text{\hspace{0.17em}}\frac{8}{3}$

For the following exercises, write the first five terms of the arithmetic series given two terms.

${a}_{1}=17,\text{\hspace{0.17em}}{a}_{7}=-31$

${a}_{13}=-60,\text{\hspace{0.17em}}{a}_{33}=-160$

$0,-5,-10,-15,-20$

For the following exercises, find the specified term for the arithmetic sequence given the first term and common difference.

First term is 3, common difference is 4, find the 5 th term.

First term is 4, common difference is 5, find the 4 th term.

${a}_{4}=19$

First term is 5, common difference is 6, find the 8 th term.

First term is 6, common difference is 7, find the 6 th term.

${a}_{6}=41$

First term is 7, common difference is 8, find the 7 th term.

For the following exercises, find the first term given two terms from an arithmetic sequence.

Find the first term or ${a}_{1}$ of an arithmetic sequence if ${a}_{6}=12$ and ${a}_{14}=28.$

${a}_{1}=2$

Find the first term or ${a}_{1}$ of an arithmetic sequence if ${a}_{7}=21$ and ${a}_{15}=42.\text{\hspace{0.17em}}$

Find the first term or ${a}_{1}$ of an arithmetic sequence if ${a}_{8}=40$ and ${a}_{23}=115.$

${a}_{1}=5$

Find the first term or ${a}_{1}$ of an arithmetic sequence if ${a}_{9}=54$ and ${a}_{17}=102.$

Find the first term or ${a}_{1}$ of an arithmetic sequence if ${a}_{11}=11$ and ${a}_{21}=16.$

${a}_{1}=6$

For the following exercises, find the specified term given two terms from an arithmetic sequence.

${a}_{1}=33\text{\hspace{0.17em}}$ and $\text{\hspace{0.17em}}{a}_{7}=-15.$ Find $\text{\hspace{0.17em}}{a}_{4}.$

${a}_{3}=-17.1\text{\hspace{0.17em}}$ and $\text{\hspace{0.17em}}{a}_{10}=-15.7.$ Find ${a}_{21}.$

${a}_{21}=-13.5$

For the following exercises, use the recursive formula to write the first five terms of the arithmetic sequence.

$-19,-20.4,-21.8,-23.2,-24.6$

For the following exercises, write a recursive formula for each arithmetic sequence.

${a}_{n}=\left\{40,60,80,...\right\}$

${a}_{n}=\left\{17,26,35,...\right\}$

${a}_{n}=\left\{-1,2,5,...\right\}$

${a}_{n}=\left\{12,17,22,...\right\}$

${a}_{n}=\left\{-15,-7,1,...\right\}$

${a}_{n}=\left\{8.9,10.3,11.7,...\right\}$

${a}_{n}=\left\{-0.52,-1.02,-1.52,...\right\}$

${a}_{n}=\left\{\frac{1}{5},\frac{9}{20},\frac{7}{10},...\right\}$

${a}_{n}=\left\{-\frac{1}{2},-\frac{5}{4},-2,...\right\}$

${a}_{n}=\left\{\frac{1}{6},-\frac{11}{12},-2,...\right\}$

For the following exercises, write a recursive formula for the given arithmetic sequence, and then find the specified term.

Find the 17 th term.

Find the 14 th term.

Find the 12 th term.

how can are find the domain and range of a relations
A cell phone company offers two plans for minutes. Plan A: $15 per month and$2 for every 300 texts. Plan B: $25 per month and$0.50 for every 100 texts. How many texts would you need to send per month for plan B to save you money?
6000
Robert
more than 6000
Robert
can I see the picture
How would you find if a radical function is one to one?
how to understand calculus?
with doing calculus
SLIMANE
Thanks po.
Jenica
Hey I am new to precalculus, and wanted clarification please on what sine is as I am floored by the terms in this app? I don't mean to sound stupid but I have only completed up to college algebra.
I don't know if you are looking for a deeper answer or not, but the sine of an angle in a right triangle is the length of the opposite side to the angle in question divided by the length of the hypotenuse of said triangle.
Marco
can you give me sir tips to quickly understand precalculus. Im new too in that topic. Thanks
Jenica
if you remember sine, cosine, and tangent from geometry, all the relationships are the same but they use x y and r instead (x is adjacent, y is opposite, and r is hypotenuse).
Natalie
it is better to use unit circle than triangle .triangle is only used for acute angles but you can begin with. Download any application named"unit circle" you find in it all you need. unit circle is a circle centred at origine (0;0) with radius r= 1.
SLIMANE
What is domain
johnphilip
the standard equation of the ellipse that has vertices (0,-4)&(0,4) and foci (0, -15)&(0,15) it's standard equation is x^2 + y^2/16 =1 tell my why is it only x^2? why is there no a^2?
what is foci?
This term is plural for a focus, it is used for conic sections. For more detail or other math questions. I recommend researching on "Khan academy" or watching "The Organic Chemistry Tutor" YouTube channel.
Chris
how to determine the vertex,focus,directrix and axis of symmetry of the parabola by equations
i want to sure my answer of the exercise
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how to solve the Identity ?
what type of identity
Jeffrey
Confunction Identity
Barcenas
how to solve the sums
meena
hello guys
meena
For each year t, the population of a forest of trees is represented by the function A(t) = 117(1.029)t. In a neighboring forest, the population of the same type of tree is represented by the function B(t) = 86(1.025)t.
by how many trees did forest "A" have a greater number?
Shakeena
32.243
Kenard
how solve standard form of polar
what is a complex number used for?
It's just like any other number. The important thing to know is that they exist and can be used in computations like any number.
Steve
I would like to add that they are used in AC signal analysis for one thing
Scott
Good call Scott. Also radar signals I believe.
Steve
They are used in any profession where the phase of a waveform has to be accounted for in the calculations. Imagine two electrical signals in a wire that are out of phase by 90°. At some times they will interfere constructively, others destructively. Complex numbers simplify those equations
Tim