The 4th term of an AP is 4 and the 8th term is 22 what is the 1st term?

Rivka Thorpe

Rivka Thorpe

Answered question

2021-05-14

The 4th term of an AP is 4 and the 8th term is 22 what is the 1st term?

Answer & Explanation

yagombyeR

yagombyeR

Skilled2021-05-15Added 92 answers

The nnth term of an arithemtic progression with a1 as the first term and dd as the common difference is given by:
an=a1+(n1)d
Using the 4th term, we write one equation:
a4=a1+(41)d
4=a1+3d (1)
Using the 8th term, we write one equation:
a8=a1+(81)d
22=a1+7d (2)
Subtract each side of (1) and (2) and solve for dd:
18=4d
4.5=d
Solve for a1 using (1):
4=a1+3(4.5)
4=a1+13.5
9.5=a1
The first term is −9.5.

Jeffrey Jordon

Jeffrey Jordon

Expert2021-08-11Added 2605 answers

Explanation

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