Question

In an AP : if a = 10, a₁₀ = 30, then d = ...........​

Answer 1

Answer:

Given, common difference of the AP,

d=5

We know that,

a

n

=a

1

+(n−1)d

Then,

a

18

=a

1

+17×d

a

13

=a

1

+12×d

Solving the two equations,

a

18

−a

13

=a

1

+17d−a

1

−12d

a

18

−a

13

=5d,

Substituting d=5,

a

18

−a

13

=25

Answer 2

Step-by-step explanation:

$a = 10 \: \: \: \: \: a {10} = 30 \: \: d = \\ \\ a10 = a + (n - 1)d \\ \\ 30 = 10 + (10 - 1) \times d \\ \\ 30 = 10 + 9d \\ \\ 30 - 10 = 9d \\ \\ \frac{20}{9} = d$

I hope it helps you..........