Answer:
Step-by-step explanation:
(x + y +z)^2 = x² + y² + z² + 2xy + 2yz + 2zx
x = a/3
y = -b/6
c = -1
[tex][\frac{a}{3}-\frac{b}{6}-1]^{2}=(\frac{a}{3})^{2}+(\frac{-b}{6})^{2}+(-1)^{2}+2*\frac{a}{3}*\frac{-b}{6}+2*\frac{-b}{6}*(-1)+2*\frac{a}{3}*(-1)\\\\\\=\frac{a^{2}}{9}+\frac{b^{2}}{36}+1-\frac{ab}{9}+\frac{b}{3}-\frac{2a}{3}[/tex]
