There two zero’s hopefully
I think it would have to be 1.46.
Explanation: if you subtract 3.56 from 2.1 you’ll get 1.46
Answer:

Step-by-step explanation:
√a^4 is the same as:
√a × √a × √a × √a
group them as 2 pairs of
(√a × √a) × (√a × √a)
which makes
a × a
which is the same as 
First, create an equation with the criteria given.
If we let x be your number,

(

is twice the product of 3 and x, and if it exceeds

by 10, then we add 10 to

to make the two sides of the equation equal.)
Now, solve for

.