（x+y)²=(√3+√2)²x²+2xy+y²=5+2√6x²-2xy+4xy+y²=5+2√6(x-y)²+4×√6=5+2√6(x-y)²=5-2√6(x-y)²=(√3-√2)²|x-y|=√3-√2