Question

The first 3 terms of an AP are x, 2x+1, 5x-1 find x and the sum of the first ten terms

Answer 1

Answer:

2x+1-x=(5x-1)-(2x+1)

x+1=3x-2

3x-x=1+2

2x=3

x=3/2. Ans

c.d=2×3/2+1-3/2

=4-3/2

=5/2

S10=10/2{2×3/2+(10-1)5/2}

=5{3+45/2}

=5×51/2

=255/2

=127.5 Ans