a) M(x)=P(x) + Q ( x) = ( x^2 + 2x -5 ) + ( x^2 - 9x+5 )
= x^2 + 2x - 5 + x^2 - 9x + 5
= ( x^2 + x^2 ) + ( 2x - 9x ) + ( -5 + 5 )
= 2x^2 + ( - 7x )
N(x) = P(x) - Q(x) = ( x^2 + 2x -5 ) - ( x^2 - 9x + 5 )
= x^2 + 2x - 5 -x^2 + 9x + 5
= [ x^2 + ( - x^2 ) ] + ( 2x + 9x ) + ( -5 + 5 )
= 11x