2018 Question Paper Solution | Question 4

This is an easy 1-mark question from the chapter Arithmetic Progressions. Concept tested: n^th term of an Arithmetic Progressions.

Question 4: In an AP, if the common difference (d) = - 4, and the seventh term (a₇) is 4, then find the first term.

Video Explanation

Explanatory Answer | Q4 2018 Board Paper

Common difference, d = -4
7th term a₇ = 4
Let a₁ be the first term of this AP.

nth term of an AP a_n = a₁ + (n - 1)d

∴ a₇ = a₁ + (7 - 1)d
4 = a₁ + 6(-4)
4 = a₁ - 24
a₁ = 28