Ta có: \(P(x) = {x^4} - 3{x^2} + \dfrac{1}{2} - x\)
a) Vì \(P(x) + Q(x) = {x^5} - 2{x^2} + 1\) nên
b) Vì \(P(x) – R(x) = {x^3}\) nên \(R\left( x \right) = P\left( x \right) - {x^3}\)
Do đó:
\(\eqalign{
& R(x) = {x^4} - 3{x^2} + {1 \over 2} - x - {x^3} \cr
& \,\,\,\,\,\,\,\,\,\,\,\,\,\, = {x^4} - {x^3} - 3{x^2} - x + {1 \over 2} \cr} \)
