Question

71
Page :
Date
of
3) What is the sum of the first 20 terms of an a.p if a =4 and t20 =36
​

Answer 1

Answer:

Sum of n terms = n/2 ( 2 a + ( n - 1 ) d ) .

Here a ( n ) = a + ( n - 1 ) d = last term = a ( 20 )

Sum = 20/2 ( 4 + 36 )

= 10 ( 40 ) = 400.

Sum of the first 20 terms is 400 .

please mark me as a brainlist

Answer 2

Answer :-

Given,

Given,a= 4

Given,a= 420th term or last term for finding sum = 36

Given,a= 420th term or last term for finding sum = 36number of term = 20

Given,a= 420th term or last term for finding sum = 36number of term = 20Sum of n term =

Given,a= 420th term or last term for finding sum = 36number of term = 20Sum of n term =(a + l) \times n \div 2(a+l)×n÷2

Given,a= 420th term or last term for finding sum = 36number of term = 20Sum of n term =(a + l) \times n \div 2(a+l)×n÷2where

Given,a= 420th term or last term for finding sum = 36number of term = 20Sum of n term =(a + l) \times n \div 2(a+l)×n÷2wherea= first term = 4

Given,a= 420th term or last term for finding sum = 36number of term = 20Sum of n term =(a + l) \times n \div 2(a+l)×n÷2wherea= first term = 4l = last term = 36

Given,a= 420th term or last term for finding sum = 36number of term = 20Sum of n term =(a + l) \times n \div 2(a+l)×n÷2wherea= first term = 4l = last term = 36and n = no. of terms = 20

Given,a= 420th term or last term for finding sum = 36number of term = 20Sum of n term =(a + l) \times n \div 2(a+l)×n÷2wherea= first term = 4l = last term = 36and n = no. of terms = 20After substituting value

Given,a= 420th term or last term for finding sum = 36number of term = 20Sum of n term =(a + l) \times n \div 2(a+l)×n÷2wherea= first term = 4l = last term = 36and n = no. of terms = 20After substituting valueSum = (4 + 36)X 20/2

Given,a= 420th term or last term for finding sum = 36number of term = 20Sum of n term =(a + l) \times n \div 2(a+l)×n÷2wherea= first term = 4l = last term = 36and n = no. of terms = 20After substituting valueSum = (4 + 36)X 20/2= 40 X 10

Given,a= 420th term or last term for finding sum = 36number of term = 20Sum of n term =(a + l) \times n \div 2(a+l)×n÷2wherea= first term = 4l = last term = 36and n = no. of terms = 20After substituting valueSum = (4 + 36)X 20/2= 40 X 10= 400

I hope it's helps you then please mark me as Brainlist so I can get next Rank Expert please.

Thanks