[tex]a)\\\\-(x-1)^2-x(x+2)=-(x^2-2x+1)-x^2-2x=- x^2+2x-1-x^2-2x=\\\\=-2x^2-1\\\\b)\\\\5-(x+1)^2+(2x-3)(x+4)=5-(x^2+2x+1)+2x^2+8x-3x-12=\\\\=5- x^2-2x-1+2x^2+5x-12= x^2+3x-8\\\\c)\\\\-(x+2y)+(-6x-9y)+(x+1)(x-1)=- x-2y -6x-9y +x^2-1=\\\\=x^2-7x-11y-1[/tex]
[tex]d)\\\\(4-a)(5+a)+(6-a)(7+a)=20+4a-5a-a^2+42+6a-7a-a^2=-2a^2-2a+62\\\\\\\\stosujemy\ wzory:\\\\(a-b)^2=a^2-2ab+b^2\\\\(a+b)^2=a^2+2ab+b^2\\\\(a+b)(a-b)=a^2-b^2[/tex]
