5x(4\(x^2\) -2x+1)-2x(10\(x^2\) -5x+2)=-36

20\(x^3\) -10\(x^2\) +5x-20\(x^3\) +10\(x^2\) -4x=-36

(20\(x^3\) -20\(x^3\) )+(-10\(x^2\) +10\(x^2\) )+(5x-4x)=-36

x=-36

a) P(x)=(\(x^4\) -5\(x^3\) +4x-5)+(-\(x^4\) +3\(x^2\) +2x+1)

=\(x^4\) -5\(x^3\) +4x-5-\(x^4\) +3\(x^2\) +2x+1

=(\(x^4\) -\(x^4\) )-5\(x^3\) +3\(x^2\) +(4x+2x)+(-5+1)

=-5\(x^3\) +3\(x^2\) +6x-4

b)P(x)=R(x)+Q(x)

R(x)=P(x)-Q(x)

=(-5\(x^3\) +3\(x^2\) +6x-4)-(-\(x^4\) +3\(x^2\) +2x+1)

=-5\(x^3\) +3\(x^2\) +6x-4+\(x^4\) -3\(x^2\) -2x-1

=\(x^4\) -5\(x^3\) +(3\(x^2\) -3\(x^2\) )+(6x-2x)+(-4-1)

=\(x^4\) -5\(x^3\) +4x-5