Well here's a way. Find the position of the first occurrence of x:
expr = HoldForm[x + 2 + 4 + x];
pos = Position[expr, x, -1, 1];
Then:
ReplacePart[expr, pos -> 4]
4 + 2 + 4 + x
2 of 2
make code more efficient by searching only for the first occurrence rather than all
Mr.Wizard
- 273.1k
- 34
- 595
- 1.4k
RunnyKine
- 33.3k
- 3
- 110
- 176