Question

计算：1/√(7+4√3)+1/√(7-4√3)

Answer 1

1/√(7+4√3)+1/√(7-4√3)
=√(7-4√3)/（49-48）+√(7+4√3)/（49-48）
=√(7-4√3)+√(7+4√3)
=√(2-√3)的平方+√(2+√3)平方
=2-√3+2+√3
=4

Answer 2

1/√(7+4√3)+1/√(7-4√3)
=[(7-4√3)+(7+4√3)]/√(7+4√3)√(7-4√3)
=14/√(49-48)
=14
通分合并

Answer 3

1/√(7+4√3)+1/√(7-4√3)
=(7-4√3)/√(7+4√3)(7-4√3)+(7+4√3)/√(7-4√3)(7+4√3)
=(7-4√3)/1+(7+4√3)/1
=7-4√3+7+4√3
=14

Answer 4

通分就可以了 答案是14

Answer 5

1/√(7+4√3)+1/√(7-4√3)

=1/√(4+4√3+3)+1/√(4-4√3+3)
=1/√(2+√3)²+1/√(2-√3)²
=1/(2+√3)+1/(2-√3)
=2-√3+2+√3
=4