Ngracem802 Ngracem802
  • 25-04-2018
  • Mathematics
contestada

If 2k, 5k-1 and 6k+2 are the first 3 terms of an arithmetic sequence, find k and the 8th term.

Respuesta :

LammettHash
LammettHash LammettHash
  • 25-04-2018
Consecutive terms in an arithmetic sequence differ by a constant [tex]d[/tex]. So

[tex]5k-1=2k+d[/tex]
[tex]6k+2=5k-1+d[/tex]
[tex]\implies\begin{cases}3k-d=1\\k-d=-3\end{cases}\implies k=2,d=5[/tex]

Denote the [tex]n[/tex]-th term in the sequence by [tex]a_n[/tex]. Now that [tex]a_1=2[/tex], we have

[tex]a_n=a_{n-1}+5=a_{n-2}+2\cdot5=\cdots=a_1+(n-1)\cdot5[/tex]

which means

[tex]a_8=2+(8-1)\cdot5=37[/tex]
Answer Link

Otras preguntas

I need to solve this p-4=-9+p
write -0.14 as a fraction or mixed number in simplest form
simplify: -3(4×-4) 7x(3+4)
"He wrote the diary in a secret shorthand."Where is the simple predicate in the sentence above?
An athlete runs 90 laps in 6 hours. This is the same as how many laps per minute? (A) 1/15 (B) 1/9 (C) 1/4 (D) 1/2 (E) 1
The Three-fifths compromise resulted in...
Write 314,207 in expanded form
How many times more basic is a solution with a pH of 10 than a solution with a pH of 8  a. A pH of 10 is two times as basic  b. A pH of 8 is two times as basic
which  property should be used next in this solution process 3x+2+3=7(x-1)-4
what decimal is equivalent to 122/11?