Question

b分之a+c=1,求证：b平方大于等于4ac

Answer 1

(a+c)/b=1;

b=a+c;

b^2=a^2+2ab+c^2=a^-2ac+c^2+4ac=(a-c)^2+4ac;

(a-c)^2>=0

所以:b^2>=4ac