The fifth term of an arithmetic sequence is 11. If the difference between two consecutive terms is 1, what is the product of the first two terms?

Answer 1

a , a+d, a+2d ..... a+(n-1)d
or
an = a +(n-1)d

a5 = a + 4 (1) = 11
so
a = 7

7 * 8 = 64-8 :)

Answer 2

56