1/3 + 7x = 1/3 + 7(5 )=
1/3+35
=1/3 + 105/3 =
106/3=
35 1/3
B is the best strategy. (You mentioned an option D, but it's not shown in your question!!)
We have the <span> Trigonometric Identities : </span>secx = 1/cosx; (sinx)^2 + (cosx)^2 = 1;
Then, 1 / (1-secx) = 1 / ( 1 - 1/cosx) = 1 / [(cosx - 1)/cosx] = cosx /
(cosx - 1 ) ;
Similar, 1 / (1+secx) = cosx / (1 + cosx) ;
cosx / (cosx - 1) + cosx / (1 + cosx) = [cosx(1 + cosx) + cosx (cosx - 1)] / [ (cosx - 1)(cox + 1)] =[cosx( 1 + cosx + cosx - 1 )] / [ (cosx - 1)(cox + 1)] = 2(cosx)^2 / [(cosx)^2 - (sinx)^2] = <span> 2(cosx)^2 / (-1) = - 2(cosx)^2;
</span>
Scientific notation for above value is ~
