Question 100682
cubed sqrt of -8/27
{{{(-8/27)^3=-512/19683}}} we cube the number
{{{sqrt(-512/19683)=16sqrt(-2)/81sqrt(3)}}} we get the square root
{{{(16sqrt(-2)/81sqrt(3))(sqrt(3)/sqrt(3) )}}}so a square root wont be in the denominator
={{{16sqrt(-6)/343=(16sqrt(6)*i)/343}}} the imaginary number {{{i=sqrt(-1)}}}
.
sqrt(63)-2 sqrt(28)+5 sqrt of (7)  
=sqrt(9*7)-2sqrt(7*4)+5sqrt(7)
=3sqrt7-4sqrt(7)+5sqrt(7)
=4sqrt(7)
Ed