a) (3x - 1)² - (2x +1)² =9x²-6x+1-(4x²+4x+1)=9x²-6x+1-4x²-4x-1=5x²-10x
b) (x + 4)² - (2x -6)² =x²+8x+16-(4x²-24x+36)=x²+8x+16-4x²+24x-36= -3x²+32x-20
c) (-2x + 3)² - \frac{1}{4}x² =4x²-12x+9-[tex] \frac{1}{16} } [/tex]=4x²-12x+[tex] \frac{144-1}{16} [/tex]=4x²-12x+[tex] \frac{143}{16} [/tex]
d) 4(x + 2)² - 9(2x - 1)² =4(x²+4x+4)-9(4x²-4x+1)=4x²+16x+16-36x²+36x-9= -32x²+52x+7
