a) w(x)=(3x−1)(x+1)−(1−3x)x2+x(3x−1)=
=(3x−1)(x+1)+(3x−1)x2+x(3x−1)=
=(3x−1)(x+1+x2+x)=
=(3x−1)(x2+2x+1) =(a2+2ab+b2=(a+b)2) (3x−1)(x+1)2
b) w(x)=(−5+2x)(x+4)−(5−2x)2−3(5−2x)x2=
=(2x−5)(x+4)−(−(2x−5))2+3(2x−5)x2=
=(2x−5)(x+4)−(2x−5)2+3x2(2x−5)=
=(2x−5)(x+4−(2x−5)+3x2)=
=(2x−5)(3x2−x+9)Δ=1−4⋅3⋅9<0
c) w(x)=(4x−1)(x−5)−(x2+5)(1−4x)−(12x2−3x)=
=(4x−1)(x−5)+(4x−1)(x2+5)−3x(4x−1)=
=(4x−1)(x−5+x2+5−3x)=
=(4x−1)(x2−2x)=x(4x−1)(x−2)
d) w(x)=(6−4x)(3x−1)+(3−2x)3+2(3x−4)(3−2x)=
=2(3−2x)(3x−1)+(3−2x)⋅(3−2x)2+(3−2x)(6x−8)=
=(3−2x)(6x−2)+(3−2x)(9−12x+4x2)+(3−2x)(6x−8)=
=(3−2x)(6x−2+9−12x+4x2+6x−8)=
=(3−2x)(4x2−1)=(3−2x)(2x−1)(2x+1)