Упростите выражение:(3^n+3^n-1/9^n-1)^2

[latex](3^n+3^n- \frac{1}{9^n} -1)^2[/latex] [latex] (-\frac{1}{9^n} -1+(1+1)*3^n)^2[/latex] [latex](-\frac{1}{9^n}-1+2*3^n)^2[/latex] [latex]Answer : (-\frac{1}{9^n}-1+2*3^n)^2[/latex]