Question

The first term of an Ap are x, 2x +1, and 5x+1 Find

x and the sum of the
l0 terms
first

Answer 1

145/2

Explanation:

d=[2x+1-x] = [5x+1 -(2x+1)]

x+1=3x

x-3x=-1

-2x=-1

x=1/2

therefore first term is 1/2

second term is 2(1/2)+1= 2

common difference d is 2-1/2=3/2

sum of first n terms is n/2 [2a+(n-1)d] where n=10

sum of first 10 terms= 10/2[2×1/2+(10-1)3/2]

=5[1+(9)3/2] =5[1+27/2] = 5[29/2] =145/2