Q1) Given that A = and B = , find the matrix such that , where is a 2 X 2 identity matrix

and

Q2) The coefficient of X in the expansion of is 3 times the coefficient of . find the value of n.

i somehow worked my way through and got r = -2. is there something wrong?

Q3) The equation of a circle is X^2 + Y^2 - 10X - 4Y + 25 = 0

Find the set of values of K if the circle touches the line Y = K.

I subbed in the value of K into the equation but i have 2 unknowns. so how?

Hope someone could help me with this! thanks! (: