Find the arithmatic sequence find a10 and an when a1=1 and a4=-11

Question

Find the arithmetic sequence find a₁₀ and a_n when a₁=1 and a₄=-11

Answer 1

a_n = a₁ + ( n-1 ) d

a₄ = a₁ + ( 4-1 ) d

-11 = 1 + 3d

-12 = 3d

-4 = d

 

a_{10 = 1 + 9(-4)}

a₁₀ = 1 - 36

a₁₀ = -35