[tex]1) \\2x^2-x(x+2) \text{ dla } x = -1\\2x^2-x^2-2x = x^2-2x = (-1)^2-2*(-1)=1+2=3\\Odp. A[/tex]
[tex]2) \\(2a-b)(b+2a)=2ab+4a^2-b^2-2ab=4a^2-b^2\\Odp.D[/tex]
[tex]3) \\a_3 = a+5\\a_2=(a+5)-1=a+5-1=a+4\\a_1=(a+5)-2=a+5-2=a+3\\\\\frac{a+5+a+4+a+3}3=\frac{3a+12}3=\frac{3(a+4)}3=a+4[/tex]
