What is 1/3(x2)=7

Answer 1

I'm not sure if it's 1/(3x²) or (1/3)x².  No matter, I'll do both.

 

1/(3x²) = 7

(1/3)*(1/7) = x²

1/21 = x²

±√(1/21) = ±(1/21)√(21) = x

 

(1/3)x² = 7

x² = 21

x = ±√21

Answer 2

I assume you mean

 

(1/3)x² = 7

 

and you seek a solution.

 

x² = 3·7 = 21

 

x = √21