The given sequence is
a₁, a₂, ...,

Because the given sequence is an arithmetic progression (AP), the equation satisfied is

where
d = the common difference.
The common difference may be determined as
d = a₂ - a₁
The common difference is the difference between successive terms, therefore
d = a₃ - a₂ = a₄ - a₃, and so on..
The sum of the first n terms is

Example:
For the arithmetic sequence
1,3,5, ...,
the common difference is d= 3 - 1 = 2.
The n-th term is

For example, the 10-term is
a₁₀ = 1 + (10-1)*2 = 19
Th sum of th first 10 terms is
S₁₀ = (10/2)*(1 + 19) = 100
Answer:
B
Step-by-step explanation:
Answer:
x = 52
y = 38
Step-by-step explanation:
Angle x is supplementary to a 128º angle.
Supplementary angles add to 180
x+128 = 180
Subtract 128 from each side
x+128-128 = 180-128
x =52
Angle x and y are complementary.
Complementary angles add to 90
x+y =90
52+y =90
Subtract 52 from each side
52-52 +y = 90-52
y = 38
Adjacent angles-
2 angles that share a common vertex, a common side and no common interior points.
The answer is ADJACENT ANGLE
Knowing that logarithm functions and exponential functions are inverse to each other, the procees to convert a logarithmic equation to its equivalent is to perform all the operations to set an equation of the typ:

,
then invert to show it equivalent form:

.
With that you have solved the equation for x.