If x^2+(1/x^2)=7, x^4+(1/x^4)=? Choose the correct option:
A) 10  B) 47  C) 12  D) 14  E) 15
-&gt; x^4+(1/x^4)=(x^2)^2+(1/x^2)^2=(x^2+1/x^2)^2-2x^2(1/x^2)=7^2-2=47.   Thus, the answer is 47.
<result>B</result>
If x^2+(1/x^2)=7, x^4+(1/x^4)=?