Question

已知lga,lgb是方程x^2-4x+1=0的两个根,则lg^2(a/b)的值是

Answer 1

lga + lgb = 4lga * lgb = 1 [lg(a/b)]^2 = [lga - lgb]^2 = (lga +lgb)^2 - 4lgalgb = 4^2 - 4 * 1 = 12