Question

1.If A = 3x^2 - 4x^3 + 2x - 5, B = 2x^3 - 2x - 9 and C = 3x^2 - 2x^3 -15, then the degree of (A + B – C) is
(A)0 (B)1 (C)3 (D)not defined
2.When x^4 - 2x^3 +12x^2 -1 is divided by x + 5, the remainder is
(A)674 (B)1174 (C)774 (D)885
3.If x + y = a and xy = b, then the value of 
1/x^3+1/y^3 is
(A)a^3-3ab divided by b^3.
(B)a^3-3ab divided by b^2.
(C)a^3-3 divided by b.
(D)a^3-3 divided by b^2
all answers with explanation plss for iit exams

Answer 1

1. i'm pretty sure that iit is a quality examination and this is a fairly simple question so I'm not going to answer this

2. this is a pretty basic application of the remainder theorem so if you don't know it you can look it up

3.
x+y=a
x^2+y^2=a^2-2xy
x^2+y^2=a^2-2b

moving on,
1/x^3+1/y^3=(a(x^2+y^2-b))/(b^3)=(a(a^2-2b-b))/(b^3)=(a^3-3ab)/(b^3)