Medium
In an AP, the first term is -5 and the common difference is -2. Which term of the AP is -9?
Explanation
Explanation
Using aₙ = a + (n-1)d, set a + (n-1)d = -9: -5 + (n-1)(-2) = -9. Solving, (n-1) = (-9 - -5)/-2 = 2, so n = 3. Thus -9 is the 3th term.
PRO TIP
Re-check your working by substituting the answer back into the original question.