Question

Tìm x,y biết:

\(x\left(x-y\right)=\dfrac{3}{10}\)và \(y\left(x-y\right)=-\dfrac{3}{50}\)

Answer 1

\(\left\{{}\begin{matrix}x\left(x-y\right)=\dfrac{3}{10}\\y\left(x-y\right)=-\dfrac{3}{50}\end{matrix}\right.\)

\(\Leftrightarrow\left(x-y\right)^2=\dfrac{3}{10}+\dfrac{3}{50}=\dfrac{9}{25}\)

\(\Leftrightarrow\left[{}\begin{matrix}x-y=\dfrac{3}{5}\\x-y=-\dfrac{3}{5}\end{matrix}\right.\)

thay vào tìm x và y

Answer 2

Ta có: x(x-y)=3/10.

y(x-y)=-3/50.

=>x(x-y)-y(x-y)=3/10-(-3/50).

=>(x-y)^2=9/25=(±3/5)^2.

=>x-y=±3/5.

+)x-y=3/5.

=>x=3/10:3/5=1/2.

=>y=1/2-3/5=-1/10.

+)x-y=-3/5.

=>x=3/10:(-3/5)=-1/2.

=>y=-1/2-(-3/5)=1/10.

Vậy:x=±1/2;y=±1/10.