Homeclass 10MathsArithmetic ProgressionsCommon Difference

Common Difference

The common difference is the fixed, constant value added to each term of an arithmetic progression to obtain the next consecutive term. Denoted by the letter d, it is the fundamental property that defines an arithmetic sequence.

Key Concepts

The common difference is calculated by subtracting any term from its succeeding term, such as the second term minus the first term.
If the common difference is positive, the arithmetic progression is increasing, and if it is negative, the progression is decreasing.
A common difference of zero results in a constant arithmetic progression where all terms in the sequence are identical.

Formula & Equation

d=anāˆ’a(nāˆ’1)d = a_n - a_(n-1)

d is the common difference, a_n is the nth term, and a_(n-1) is the immediately preceding term.

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Common Misconceptions

Myth: Students often calculate the common difference by subtracting the second term from the first term.
Fact: You must always subtract the preceding term from the succeeding term, such as a2 minus a1, to get the correct mathematical sign for the common difference.

Real World Applications

Adding a fixed amount of 50 rupees to a savings account every month, where 50 is the common difference.
The uniform decrease in the length of ladder rungs from bottom to top by 2 centimeters, making the common difference negative 2.

Frequently Asked Questions

Can the common difference of an arithmetic progression be zero?
Yes, if the common difference is zero, the sequence is a constant arithmetic progression where every term is the exact same number.
How do you find the common difference if only the first and last terms are given?
You can use the nth term formula, an = a + (n-1)d, and solve for d if you know the total number of terms in the sequence.

Keep Learning

Arithmetic ProgressionTerm of an Arithmetic ProgressionGeneral Form of an Arithmetic Progression