3. [tex](2x-3y)^{2} = 4x^{2}+9y^{2}-12xy[/tex]
4. Obwód = 2*(2x+3) + 2(4x-1) = 4x + 6 + 8x - 2 = 12x + 4
Pole = (2x+3)(4x-1) = [tex]8x^{2} -2x+12x-3=8x^{2} +10x-3[/tex]
5. P1 = 4a*(2a+3) = [tex]8a^{2} +12a[/tex]
P2 = (2a+1)(2a-2) = [tex]4a^{2} -4a+2a-2[/tex]
P1-P2 = [tex]8a^{2} +12a - 4a^{2} -2a+2=4a^{2} +10a+2[/tex]
