# How to simplify only one side of an equality?

Suppose we have two expressions and == between them. I want to simplify only the right-hand side. What should I do?

• Also, #[[1]] == Simplify[#[[2]]] &@equation or ReplacePart[equation, 2 -> Simplify[equation[[2]]]] Nov 26 '21 at 12:39
• Alternative: Simplify[equation[[2] ] Nov 26 '21 at 12:39
• @UlrichNeumann did not you forget a brace? Nov 26 '21 at 14:31
• @Anixx: Yes, Simplify[equation[[2]] ] Nov 26 '21 at 14:46

## 1 Answer

equation = y + z  == D[Integrate[1/(x^3 + 1), x], x]


You can use MapAt:

MapAt[Simplify, equation, {2}]