Question

Find the 60th term of tge ap 8,10,12... If it has a total of 60 terms hence find the sum of its last ten terms

Answer 1

Answer:

see the image for answer

Answer 2

$\Large{\textbf{\underline{\underline{According\;to\;the\;Question}}}}$

Here,

Assume,

First term be a

Common difference be d

First term,

k = 8

Common difference,

d = 10 - 8

d = 2

Using Formula,

a(n) = a + (n - 1)d

So,

a(60) = 8 + (60 - 1) × 2

a(60) = 8 + 59 × 2

a(60) = 126

Also,

a(51) = 8 + (51 - 1) × 2

a(51) = 8 + 50 × 2

a(51) = 8 + 100

a(51) = 108

Now,

Sum of last terms

= a(51) + a(52) + ..... + a(60)

So,

S(10) = 10/2{2 × 108 + (10 - 1)2}

S(10) = 10/2{216 + 18}

S(10) = 10 × 234

S(10) = 1170

Therefore,

Sum of last 10 terms is 1170