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Find the 9th term of the arithmetic sequence 4x+44x+4, 9x+119x+11, 14x+18, 14x+18,...

User Philipk
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1 Answer

5 votes

Answer:

T9=60

Explanation:

step 1: solve for x

it is an arithmetic pattern,so the 1st difference is the common difference (d)

therefore...9x+199x+11-(4x+44x+4)=14x+18-(9x+199x+11)

128x+11-48x-4=14x+18-128x-11

80x+7=-144x+7

80x+144x=7-7

224x=0

224x/224=0/224

X=0

step 2: substitute for x

4(0)+44(0)+4=4[1st term]

9(0)+119(0)+11=11(2nd term)

14(0)+18=18(3rd term)

step 3:find the common difference

d=3rd term- 2nd term, 2nd term-1st term

3rd term-2nd term

18-11=7

2nd term-1st term

11-4=7

therefore...d=7

step 4:find the general formula

we use the formula Tn=a+(n-1)d to find the general formula/ nth term

where: Tn is the nth term

a is the first term

n is the number of term

d is the common difference

Tn=a+(n-1)d

=4+(n-1)7

=4+7n-7

=7n-3

step 5:find the 9th term

Tn=a+(n-1)d

=7n-3

=7(9)-3

=60

User Atiretoo
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