Case Study

Look at 942x49\sqrt[4]{42x} and 242x42\sqrt[4]{42x}. Name the two conditions that make these like radicals, then find their sum.

Case context: Like radicals combine the same way like terms combine.

Question: Look at 942x49\sqrt[4]{42x} and 242x42\sqrt[4]{42x}. Name the two conditions that make these like radicals, then find their sum.

Sample answer: The two conditions are: (1) same index (both are 4th roots), and (2) same radicand (both are 42x42x). Since they are like radicals, add the coefficients and keep the radical part unchanged: 942x4+242x4=1142x49\sqrt[4]{42x} + 2\sqrt[4]{42x} = 11\sqrt[4]{42x}.

Key points:

  • Like radicals must have the same index
  • Like radicals must have the same radicand
  • Add or subtract only the coefficients
  • The radical part does not change

Rubric: Full credit requires stating both conditions (same index, same radicand) and correctly showing that only the coefficients are added while the radical part stays the same, with the correct sum 1142x411\sqrt[4]{42x}.

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Updated 2026-07-09

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