Great . Of course , we can expand the whole thing and combine terms which will produce x^7 but it would be tedious and risky so its better to use the binomial theorem :
so now lets see what values of k give 7
14-3k=7 , k=7/3 and this cant be since k must be +ve integer
how about 16-3k=7 , k=3 .
its coefficient is
I didnt quite understand "so now lets see what values of k give 7
14-3k=7 , k=7/3 and this cant be since k must be +ve integer
how about 16-3k=7 , k=3 ."
Does this shows that if the value of r is not a whole number, we have to round the number off and see if the power of x is what we are after?