JEE Advanced2010MathematicsMatricesActual
Paragraph: Let p be an odd prime number and T_p be the following set of 2 2 matrices T_p= A= [ array ll a & b c & a array ] ; a, b, c 0,1,2, , p-1 Question: The number of A in T_p such that det (A) is not divisible by p , is
Options
- A2 p^2
- Bp^3-5 p
- Cp^3-3 p
- Dp^3-p^2
Correct answer
D. p^3-p^2
Step-by-step solution
The number of matrices for which p does not divide Tr (A)=(p-1) p^2 of these (p-1)^2 are such that p divides |A| . The number of matrices for which p divides Tr (A) and p does not divides |A| are (p-1)^2 aligned & Required number & =(p-1) p^2-(p-1)^2+(p-1)^2 & =p^3-p^2 aligned