I could not find one solution with root function

Read the error message carefully!

The function root() when given an interval finds only zeros where the curve crosses the x-axis, but not those where, as in your case, the curve only touches the x-axis. Therefore it is also required (see error message) that the function values at the interval boundaries must have different signs.
You could try the root() function without interval specification but with a guess value.

In your case the equation is quite simple and can be solved exactly.

Primes "new" symbolic unfortunately is not very capable in terms of user friendliness as it gives us

Compare this with the result of the old symbolic engine (muPad) in Prime 6