Exercise 2.2

 (5) Find  the number of (i) 6 (ii) 7 letter palindromes that can be formed using the letters of the word 

'EQUATION'

using the letters of the word EQUATION(which contain 8 letters)
no.of 6 digits pallindroms $={\mathrm{n}}^{\frac{\mathrm{r}}{2}}=8^{\frac{6}{2}}=8^3$
 

Fill last 3 places in 8³ ways first 3 plases takes same alphabet from last  3 places
no.of 7 digits pallindrames $={\mathrm{n}}^{\frac{\mathrm{r}+1}{2}}=8^{\frac{7+1}{2}}=8^4$