Why are radicals simplified before adding and subtracting? explain your reasoning by adding sqrt8 and sqrt32 algebraically. compare the process to multiplying and dividing.

The first reason is that square root extraction is NOT a linear process, i.e.
√a + √b ≠ √(a+b) unless a = b. What usually happens is that some common factors can be gotten out frpom the radical and then the distributive law allows some consolidation of terms.
sqrt(8) + sqrt(32) = 2sqrt(2) + 4sqrt(2) = 6 sqrt(2)

but sqrt(8) + sqrt(24) = 2sqrt(2) + 2sqrt(6) = 2[sqrt(2) + sqrt(6)].