Mathematics - Permutation & Combination Question with Solution | TestHub

$G_1:3,6,9\dots \dots ..3n$ $\begin{array}{rlrl}& G_2:1,4,7\dots \dots (3n-2)& G_3:2,5,8\dots \dots .(3n-1)& a^2-b^2=(a-b)(a+b)\end{array}$

Either $\mathrm{a}-\mathrm{b}$ is divisible by 3 (or) $\mathrm{a}+\mathrm{b}$ is divisible by 3 (or) both $\begin{array}{rlr}& n{c}_2+n{c}_2+n{c}_2+n{c}_1\cdot n{c}_1& 3\frac{n(n-1)}{2}+n^2\end{array}$