Question

An arithmetic series has a first term of 4. The sum of the first 40 terms is 6080. Find the value of the 40th term.

Answer 1

Look , use the sum of the arithmetic term equation

which is

\[Sn = \frac{ n }{ 2 } (a + an ) \]

Answer 2

where Sn = sum of terms
n = number of terms
a = the first term
an = is the last term

these are all with known value except for ( an ) right ?

Answer 3

substitute the values ..

Sn = 6080
a = 4
n = 40

Answer 4

OKay

Answer 5

you got it ?

Answer 6

6080 = 40/2 (4+an)

Answer 7

@Lama97

Answer 8

right .. now put ( an ) the subject of the formula ..

Answer 9

Will you help me solve

Answer 10

ok