Question

If twelfth term of an A.P is 30, then the sum of its fifth, twelfth and nineteenth term is 90 30 60 45

Answer 1

Answer:

• sum of fifth, twelfth and nineteenth terms of AP is 90 .

Step-by-step explanation:

[ nth term of an AP is given by ; aₙ = a + ( n- 1 ) d ]

Let us take first term of AP = a

and. common difference of AP = d

then,

Given that, twelfth term of AP is 30

so,

• a₁₂ = 30  

• a + 11 d = 30  .... eqn (1)

Now,

we need to find sum of its fifth , twelfth and nineteenth terms

•  a₅ + a₁₂ + a₁₉ = ?

so,

Let, a₅ + a₁₂ + a₁₉ = x

→ x = a₅ + a₁₂ + a₁₉

→ x = a + 4 d + a + 11 d + a + 18 d

→ x = 3 a + 33 d

→ x = 3 ( a + 11 d )

[ using equation (1) ]

→ x = 3 ( 30 )

→ x = 90

therefore,

sum of fifth, twelfth and nineteenth terms of AP is 90 .

Answer 2

Step-by-step explanation:

for right answer click on the above image

hope it helps u