a) (4x - 3)(x + 2) = 4x(x + 2) - 3(x + 2) = 4x2+5x−6.
b) (5x+2)(−x2+3x+1) = 5x.(−x2+3x+1)+2(−x2+3x+1) = −5x3+13x2+11x+2.
c) (2x2−7x+4)(−3x2+6x+5)=2x2(−3x2+6x+5)−7x(−3x2+6x+5)+4(−3x2+6x+5)=−6x4+33x3−44x2−11x+20