Class 10 Maths Chapter 5 – Arithmetic Progressions | NCERT Solutions, Formulas & CBSE Board Questions (2025–26)
Class 10 CBSE Maths – Chapter 5: Arithmetic Progressions 🔹 Key Concepts and Formulas ✅ What is an Arithmetic Progression (AP)? An AP is a list of numbers in which the difference between any two consecutive terms is constant. Let the first term be a a and the common difference be d d . Then the AP is: a , a + d , a + 2 d , a + 3 d , … a, a + d, a + 2d, a + 3d, \ldots ✅ Important Formulas General Term (n-th term) of an AP : a n = a + ( n − 1 ) d a_n = a + (n - 1)d Where: a a = First term d d = Common difference n n = Term number Sum of first n terms of an AP : S n = n 2 [ 2 a + ( n − 1 ) d ] or S n = n 2 ( a + l ) S_n = \frac{n}{2} [2a + (n - 1)d] \quad \text{or} \quad S_n = \frac{n}{2} (a + l) Where: a a = First term l l = Last term = a + ( n − 1 ) d a + (n - 1)d n n = Number of terms 🔹 📘 NCERT Solved Examples (Highlights) Example 1: Find the 10th term of the AP: 2, 7, 12, 17, ... a = 2 , d = 5 , n = 10 ⇒ a n = a + ( n − 1 ...