let b be a positive integer and a =b^2-b . If b >= 4 , then a^2-2a is divisible by : a) 15 b)20 c) 24 d) All of the above

If the constant term of (2x-1/x)^n is -160 ! Find n

Solve the equation:x^4-2x^3+4x^2+6x-21=0 if two of its roots are equal in magnitude but opposite in sign .

X=2+2^2/3+2^1/3, then the value of x^3-6x^2+6x?

A dishonest dealer claims to sell a product at its cost price . He uses a counterfeit weight which is 20% less than the real weight . Further he added...