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
Answer:
m<1 = 105°
m<2 = 75°
very simple explanation:
a and b are perpendicular. line t intersects these perpendicular lines. the given 75° is, in short, an intersect of a line, which is 180°. 75-180=105. angles 1 and 2 are duplicates of what is shown
Answer:
Step-by-step explanation:
Simplifying
2m + -6n + 5n + 3m = 0
Reorder the terms:
2m + 3m + -6n + 5n = 0
Combine like terms: 2m + 3m = 5m
5m + -6n + 5n = 0
Combine like terms: -6n + 5n = -1n
5m + -1n = 0
Solving
5m + -1n = 0
Solving for variable 'm'.
Move all terms containing m to the left, all other terms to the right.
Add 'n' to each side of the equation.
5m + -1n + n = 0 + n
Combine like terms: -1n + n = 0
5m + 0 = 0 + n
5m = 0 + n
Remove the zero:
5m = n
Divide each side by '5'.
m = 0.2n
Simplifying
m = 0.2n
Each Interior Angle = 180° - (360 / sides)
144 = 180 - (360 / sides)
(360 / sides) = 36
sides = 360 / 36
sides = 10
It is a decagon.
Source:
http://www.1728.org/polygon.htm
