karthiknayal2 karthiknayal2

25-06-2020
Mathematics

contestada

find the sum of 1st 20 terms of an AP in which third term is 7and 7th term is 2more than thrice of its 3rd term

Respuesta :

dannielle dannielle

25-06-2020

Answer:

S=740

Step-by-step explanation:

a3=7

a7=3*a3+2=3*7+2=23

a7=a3+4r

23=7+4r

-7 -7

16=4r

r=16/4

r=4

a20=a7+13r

a20=23+13*4

a20=23+52

a20=75

a1=a3-2r

a1=7-2*4

a1=7-8

a1=-1

S=(a1+a20)*20/2=(-1+75)*10=74*10=740

Answer Link

Otras preguntas

What does the Cabinet have to be approved by?.

the ninth week after conception until birth, the period during which the organs of the develping person grow in size and mature in functioning.

Encuentre las coordenadas del punto P a lo largo del segmento de línea dirigida AB, desde A(1, 6) a B(-2,-3), de modo que la razón de AP a PB sea de 5 a 1

an increase in consumer spending will most likely cause the price level and real gdp to change in which of the following ways in the short-run?

Which best describes the quaternary structure of a protein?.

What part of a quarter is the sum of three pennies, one nickel, and one dime?

The reverse leakage current of a transistor when connected to CB configuration is 0.2A and it is 18A when the transistor is connected in CE configuration. Calcu

FILL IN THE BLANK. deadlock ___requires that the operating system be given, in advance, additional information concerning which resources a process will request

Choose the correct description for each phase of mitosis. Label A DONE Intro

Acknowledging the demand for healthier drinking options, a large beverage company has developed a new line of beverages with no calories and no artificial sweet