Question

giảng hộ em câu 10 với ạ

Answer 1

\(a>b\Rightarrow a-b>0\)

\(P=\dfrac{a^2+b^2-2ab+2ab+1}{a-b}=\dfrac{\left(a-b\right)^2+9}{a-b}=a-b+\dfrac{9}{a-b}\ge2\sqrt{\dfrac{9\left(a-b\right)}{a-b}}=6\)

\(P_{min}=6\) khi \(\left(a;b\right)=\left(4;1\right);\left(-1;-4\right)\)