Question

if third of an a.p is 12 and 10th term is 26 then it's 20th trem is

Answer 1

a+2d=12----------(1)
a+9d=26----------(2)
sub (1) from (2)
-7d=-14
d=2
put d=2 in (1)
a=8
now 20th term is
a+19d
8+19×2
8+38
46
i.e the 20th term of the given ap is 46

Answer 2

≡QUESTION≡

If third of an AP is 12 and 10th term is 26 then it's 20th term is?

                                                         

║⊕ANSWER⊕║

GIVEN

3rd term of the AP = 12

=> a + 2d = 12....(1)

10th term of the AP = 26

=> a + 9 d = 26....(2)

(1) - (2)

=> a + 2d - a - 9d = 12 - 26

=> -7d = -14

=> d = 2

Substituting d = 2 in eq (1)

a + 4 = 12

a = 8

The 20th term = a + 19 d

                        = 8 + 19 (2)

                        = 8 + 38

                        = 46