Answer:
Hence, ption B is true.
Step-by-step explanation:
Given the expression
solving the expression
as
so the expression becomes
Group like terms
Add similar elements
Therefore, we conclude that:
Hence, option B is true.
Answer:
see explanation
Step-by-step explanation:
The nth term of an AP is
= a₁ + (n - 1)d
where a₁ is the first term and d the common difference
Given a₅ is double a₇ , then
a₁ + 4d = 2(a₁ + 6d) , that is
a₁ + 4d = 2a₁ + 12d ( subtract a₁ from both sides )
4d = a₁ + 12d ( subtract 12d from both sides )
- 8d = a₁
The sum of n terms of an AP is
=
[ 2a₁ + (n - 1)d ] , substitute values
=
( 2(- 8d) + 16d)
= 8.5(- 16d + 16d)
= 8.5 × 0
= 0