1

Let \$a_n\$ be the arithmetic progression.If \$a_1 = 10 , a_2 = 20\$.

Determine \$a_59\$

2

Difference between two consective numbers

\$ d = a_n - a_(n-1) \$

3

Substitute the \$a_1 , a_2 \$

\$ d = a_2 - a_1 \$

4

Substitute the \$a_1 = 10 , a_2 = 20\$

\$d = 20 - 10 \$ = 10

5

Formula for \$n_(th)\$ number of series

\$ a_n = a_1 + (n-1)d \$

6

Substitute d = 10 , n = 59 we get

\$ a_59 = 10 + (59-1)10 \$

7

Simplify

\$ a_59 = 10 + (58)10 \$

\$ a_59 = 10 + 580 \$

8

Answer

C ⇒ \$a_59 = 590\$