Question

How many integral solutions are there for the equation A+B+C = 10 where A $\ge$ 1, B $\ge$ 2, C $\ge$ 3 ?

• A. ⁵C₂
• B. ⁶C₂
• C. ¹²C₂
• D. ⁸C₂
• E. None of these

Answer 1

The correct option is B ⁶C₂

This is a question based on SàD with a varying lower limit.

Take out 1+2+3=6 from the RHS. Equation changes to

A+B+C = 4. Answer will the arrangement of 4 zeroes and 2 ones = ${}^6$C${}_2$