Question

If a1 = 7 and an = an-1 + 4 then find the value of a4.

Answer 1

Put values get answer

• a_n=a_(n-1)+4
• a_4=a_3+4
• a_4=a_2+4+4
• a_4=a_1+4+4+4
• a_4=7+12
• a_4=19

Answer 2

`a_4=19`

Explanation:

Given:

• 
  `a_1=7`

• 
  `a_n=a_(n-1)+4`

`\implies a_2=a_(1)+4=7+4=11`

`\implies a_3=a_(2)+4=11+4=15`

`\implies a_4=a_(3)+4=15+4=19`