Put \(\left(2k-1\right)\left(2k+1\right)=123476543\)

\(\Leftrightarrow4k^2-1-123476543=0\)

\(\Leftrightarrow4k^2-123476544=0\)

\(\Leftrightarrow4\left(k^2-30869136\right)=0\)

\(\Leftrightarrow k^2=30869136=5556^2\)

\(\Leftrightarrow k=5556\)

\(\Rightarrow\left\{{}\begin{matrix}2k-1=11111\\2k+1=11113\end{matrix}\right.\)

Ans : 11111 & 11113.

Put (2k−1)(2k+1)=123476543

⇔4k2−1−123476543=0

⇔4k2−123476544=0

⇔4(k2−30869136)=0

⇔k2=30869136=55562

⇔k=5556

⇒{2k−1=111112k+1=11113

Ans : 11111 & 11113.

123476543 = 11111 x 11113

123476543 = 11111 x 11113