Hard
In an AP, the first term is 8 and the common difference is 4. Which term of the AP is 20?
Explanation
Explanation
Using aₙ = a + (n-1)d, set a + (n-1)d = 20: 8 + (n-1)(4) = 20. Solving, (n-1) = (20 - 8)/4 = 3, so n = 4. Thus 20 is the 4th term.
PRO TIP
Re-check your working by substituting the answer back into the original question.