Question

已知X = 3/（根号7-3） ,a 是 X 的整数部分,b 是 X 的小数部分,求a-b╱a+b的值?

Answer 1

X=3/(√7-3)=3(√7+3)/(-2)=-3/2(√7+3),

a=-9,b=3/2(3-√7),

a-b=-9-3/2(3-√7)=-3/2(9-√7)

∴(a-b)/(a+b)

=-3/2(9-√7)*(√7-3)/3

=-1/2(-34+12√7)

=17-6√7.