Answer:
16 + 3n
Step-by-step explanation:
a = 19 ; common difference = 22 - 19 = 3
a(n) = a + (n -1 ) *d
= 19 + (n-1)*3
= 19 + 3n - 3
= 16 + 3n
Since y=x+3 (given)
Put value of y in equation x+y=(-3)
x+x+3=(-3)
2x=(-6)
x=(-3)
Put x=(-3) in x+y=(-3)
(-3)+y=(-3)
y=0
So, x=(-3)
y=0
P=7+7+12+12P=14+24P=38
See the attachment for diagram
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