I think...but am not absolutely sure...that you have the reverse of the usual problem, namely too many parentheses!
Your numerator is log x7
Your denominator is sqrt(3)*(y2z)
and then you have an extra )
What I suggest you do is use sqrt(.....) for your square root function instead of the \root notation and try using [....] and {....} to clarify which parentheses are intended to enclose what.