a) = [tex]x^{2} -x+ \frac{1}{4} + \frac{ x^{2} }{4} - \frac{4x}{2}+4+ \frac{ x^{2} }{4} -( \frac{9x ^{2} }{4} + \frac{12x}{2} +4)=[/tex][tex] x^{2} -x+ \frac{1}{4} + \frac{ x^{2} }{4} - 2x+ \frac{ x^{2} }{4} -( \frac{9x ^{2} }{4} +6x+4)=[/tex][tex] x^{2} -x+ \frac{1}{4} + \frac{ x^{2} }{4} -2x+ \frac{ x^{2} }{4}- \frac{9x ^{2} }{4} -6x-4= [/tex][tex]- \frac{3}{4} x ^{2} -9x- \frac{15}{4} [/tex]
