Question

已知A方-4A+9B方+6B+5=0,求A分之1-B分之1的值.

Answer 1

A方-4A+9B方+6B+5=0 ===>

a^2 - 4a + 4 + 9b^2 + 6b + 1 = (a-2)^2 + (3b+1)^2 = 0

两个平方之和为0,则各自为0.

a = 2

b = -1/3

1/A - 1/B = 1/2 - -3 = 3.5