Question

先化简,再求值:(根号a+根号b)的平方-(根号a-根号b)的平方,其中a=1+根号2,b=根号2-

b=根号2-1

Answer 1

答：
(√a+√b)²-(√a-√b)²
=(√a+√b+√a-√b)(√a+√b-√a+√b)
=2√a*2√b
=4√(ab)
=4√[(1+√2)(√2-1)]
=4√(2-1)
=4