Question 305358
if n is a positive number,which of the following is equal to 8n ? 

<pre><font size = 4 color = "indigo"><b>

(A) {{{sqrt(64n)}}} 

{{{sqrt(64n)=sqrt(64)sqrt(n)=8sqrt(n)}}}

Nope, that's not {{{8n}}}


(B) {{{sqrt(8n^2)=sqrt(4*2*n^2)=sqrt(4)sqrt(2)sqrt(n^2)=2*sqrt(2)*n = 2n*sqrt(2)}}} 


Nope, that's not {{{8n}}}


(C) {{{sqrt(16n^2)=sqrt(16)sqrt(n^2)=4n}}} 

Nope, that's not {{{8n}}}


(D) {{{2sqrt(4n)=2sqrt(4)sqrt(n)=2*2*sqrt(n)=4sqrt(n)}}} 

Nope, that's not {{{8n}}}


(E) {{{4sqrt(4n^2)=4sqrt(4)sqrt(n^2)=4*2*n=8n}}} 

Yeppers, that's {{{8n}}}

So (E) is the correct choice

Edwin</pre>