Example 1: 2015 P1 8ii
Example 2: 2015 P1 2ii
Graphical approach will yield x> 1.732. Notice Cambridge answer is not rounded to x>1.74 to satisfy the non-rounded inequality but rounded to 3 s.f.
Considering example 1 and example 2, we conclude that in real life applications questions, when rounding off your answer to 3 s.f, round off such that the rounded off answer still satisfies the non-rounded off inequality.