Question

2+4+6+8+......=10,100,find the total numbet of terms of an A.P​

Answer 1

Step-by-step explanation:

a= first term = 2

d= common difference = 4-2= 2

sum of ap= n/2(2a+(n-1)d)

n/2(4+(n-1)2)= 10100

n(4+2n-2)= 20200

n(2n+2)=20200

2n(n+1)= 20200

n(n+1)= 10100

n²+n-10100= 0

n²-101n+100n-10100= 0

n(n-101)+100 (n-101)= 0

n= -100, 101