Question

Tìm x , y biet : x . ( x - y ) = 44/3

                       y . ( x - y ) =11/9

Answer 1

Trừ 2 vế với nhau bạn ạ!Trừ đi rồi bắt đầu tìm x và y!

 

Answer 2

\(x\left(x-y\right)=\frac{44}{3}\left(1\right)\)

\(y\left(x-y\right)=\frac{11}{9}\left(2\right)\)

Trừ (1) cho (2),vế theo vế ta được:

\(x\left(x-y\right)-y\left(x-y\right)=\frac{44}{3}-\frac{11}{9}\)

\(=>\left(x-y\right)^2=\frac{121}{9}=\left(\frac{11}{3}\right)^2=\left(-\frac{11}{3}\right)^2\)

\(=>x-y=\frac{11}{3}\) hoặc \(x-y=-\frac{11}{3}\)

+ \(x-y=\frac{11}{3}\)

Lại có \(x\left(x-y\right)=\frac{44}{3}=>x=\frac{44}{3}:\frac{11}{3}=\frac{44}{11}=4\)

\(y\left(x-y\right)=\frac{11}{9}=>y=\frac{11}{9}:\frac{11}{3}=\frac{1}{3}\)

+\(x-y=-\frac{11}{3}\)

Lại có  \(x\left(x-y\right)=\frac{44}{3}=>x=\frac{44}{3}:\left(-\frac{11}{3}\right)=\frac{44}{-11}=-4\)

\(y\left(x-y\right)=\frac{11}{9}=>y=\frac{11}{9}:\left(-\frac{11}{3}\right)=-\frac{1}{3}\)

Vậy \(x=4;y=\frac{1}{3}\) hoặc \(x=-4;y=-\frac{1}{3}\)