We rewrite 78 as 80 – 2 to use the subtraction identity with a = 80 and b = 2. Combining their squared values and subtracting the double product gives the final result.
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We evaluate this calculation by changing the number 78 into the expression 80 – 2. This lets us use the standard subtraction square identity where a is set to 80 and b is set to 2. The square of 80 is 6400, and the square of 2 is 4. The product term to subtract is two multiplied by 80 multiplied by 2, which is 320. Computing 6400 minus 320 plus 4 yields 6084.
For more NCERT Solutions for Class 9 Maths Ganita Manjari Chapter 4 Exploring Algebraic Identities (2026-27):
https://www.tiwariacademy.com/ncert-solutions/class-9/maths/ganita-manjari-chapter-4/