`(666 . . . .6)^(2) . . . ("n-digits")+(888 . . . .8)` . . . (n-digits) is equal to

underset("n-digits")((666 . . . .6)^(2))+underset("n-digits")((888 . . . .8)) is equal to

underset("n-digits")((666 . . . .6)^(2))+underset("n-digits")((888 . . . .8)) is equal to

underset("n-digits")((666 . . . .6)^(2))+underset("n-digits")((888 . . . .8)) is equal to

(666…..n "digits")^2 + (888 ... n digits) is equal to

(666 ..... ndigits) ^ (2) + (888 ..... ndigits) =

underset("n-digits")((666"……"6))^(2) +underset("n-digits") (( 888"…" 8 )) is equal to :

(666 …. N digits)^(2) + (888 …. N digits ) =

Prove that the number (444.........4)/(ndigit),(888..........89)/((n-1)digit) is a perfect square of the number (666.......6)/((n-1)digit)7

(666...n times)^2 +(888..n times) is equal to ___