sar2ietrelorev sar2ietrelorev

25-05-2016
Mathematics

contestada

What is the sum of the first 45 terms of the following sequence? 20, 18, 16, . . .
a. 1,080
b. 1,420
c. 1,530
d. 1,980

Respuesta :

Аноним Аноним

26-05-2016

Sn = (a1+an)* n / 2
an = a1+d(n-1)

d = 18-20 = -2
a45 = a1+d(45-1) = 20 - 2*(45-1) = -68
S45 = (20-68)*45/2 = -1080

Answer Link

Otras preguntas

Read the sentence.She had heard that the figure skaters were arriving.What are the helping verbs in the verb phrases?

What is the average mass of a single phosphorus atom in grams?

Joseph has started completing the square on the equation 3x^2 - 7x + 12 = 0. He has worked to the point where he has the expression x^2-7/2 x = -4. Show work to

will go to her family reunion next summer what kind of sentence is this

Which direction will the wind blow at the red spot between the high and low pressure regions?

The chairlift at a ski resort rises a total of 2600 feet from where it starts. The angle of elevation is about 22.3 degrees . How far do riders travel on the li

In Spanish, why are the present-tense verbs for TO COMPETE considered to be stem-changing verbs? A. Because, in some of them, when E is stressed, it is change

Which of the following choices is the BEST example of a complete paragraph? A. Pets are great. Many families have pets. They can be a dog, a cat, or a fish.

Which factor made it most difficult for soldiers to cross the area between the trenches? A. The land was too wide to be crossed. B. The land was not claimed

What marked the end of the Cattle kingdom?