There are two solutions. The other tutor did not get both solutions.
I'll go into a little more detail.
Raise both sides of the equation to the reciprocal of
power, which is the
power:
Remove the parentheses on the left by multiplying the exponents
which just gives the exponent 1.
On the right we use the rule:
But since the root we are taking is even, the fourth root,
there are two fourth roots, positive and negative, so we must
precede it by ±:
So there are two solutions,
and
Edwin