NCERT Example - Product increments - We Distribute, Yet Things Multiply
Question: For the product ab, by how much does the product change if (i) b increases by 1, (ii) both a and b increase by 1, (iii) a increases by 1 and b decreases by 1?
Answer: Increases: (i) a (ii) a+b+1 (iii) change = b-a-1.
Full step-by-step NCERT solution with diagrams on Something by Zero.