(ax+by)²+(ay-bx)²

(ax+by)²+(ay-bx)²

원본=a&\#178;x²+2abxy+b²y²+a²y²-2abxy+b²x²=(a²x²+a²y²)+(b²x²+b²y²)=a²(x²+y²)+b²(x²+y²)=(x²+...