257 sci cu grau si 97 saci cu porumb cantaresc 14.480,iar 349 saci cu grau si 97 saci cu porumb cantaresc 18.344 kg.Sa se afle c
1 answer:
You might be interested in
Answer:
a₁ = - 24
Step-by-step explanation:
The n th term of an AP is
= a₁ + (n - 1)d
where a₁ is the first term and d the common difference
Given a₇ = 2a₅ , then
a₁ + 6d = 2(a₁ + 4d) = 2a₁ + 8d ( subtract 2a₁ + 8d from both sides )
- a₁ - 2d = 0 → (1)
The sum to n terms of an AP is
=
[ 2a₁ + (n - 1)d ]
Given = 84 , then
(2a₁ + 6d) = 84
3.5(2a₁ + 6d) = 84 ( divide both sides by 3.5 )
2a₁ + 6d = 24 → (2)
Thus we have 2 equations
- a₁ - 2d = 0 → (1)
2a₁ + 6d = 24 → (2)
Multiplying (1) by 3 and adding to (2) will eliminate d
- 3a₁ - 6d = 0 → (3)
Add (2) and (3) term by term to eliminate d
- a₁ = 24 ( multiply both sides by - 1 )
a₁ = - 24
Integration will be ln | ( x /9 ) + ( ) | + c .
Given ∫ 1 dx / ( - 81 )
Put ,
x = 9 secθ
dx = 9 secθ tanθ dθ
and
= 9 tanθ
Substituting values in ∫ 1 dx / ( - 81 ) ,
∫ (9 secθ tanθ ) dθ / ( 9 tanθ )
∫ secθ dθ = ln | secθ + tanθ | + c
= ln | ( x /9 ) + ( / 9 ) | + c
= ln | ( x /9 ) + ( ) | + c
Hence , the integration will be ln | ( x /9 ) + ( ) | + c .
To learn more on integration follow link :
#SPJ4