If X+6, 2x+1, 4x-13,... Form An Arithmetic Sequence Find The 5th Term. (Show Your Solution).
If x+6, 2x+1, 4x-13,... Form an arithmetic sequence find the 5th term. (Show your solution).
Answer:
The fifth term (a₅) is 31.
Step-by-step explanation:
Given:
a₁ = x+6
a₂ = 2x+1
a₃ = 4x-13
Find the value of x:
a₂ - a₁ = a₃ - a₂ ⇒ common difference formula
2x+1 - (x+6) = 4x-13 - (2x+1)
2x + 1 - x - 6 = 4x - 13 - 2x - 1
2x - x - 4x + 2x = -13 - 1 - 1 + 6
-x = -9
x = 9
The sequence:
a₁ = x+6 ⇒ 9=6 = 15
a₂ = 2x+1 ⇒ 2(9)+1 = 19
a₃ = 4x-13 ⇒ 4(9)-13 = 23
The sequence is: 15, 19, 23
The common difference (d) is 4.
Find the 5th term:
n = 5
a₁ = 15
an = a₁ + (n-1)(d) ⇒ General Rule
a₅ = 15 + (5-1)(4)
a₅ = 15 + 16
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