Решите пж системы, сегодня нужно 1) lgx-lgy=2 x-10y=900 2) lgx-lgy=7 lgx+lgy=5

1) [latex] \left \{ {{lg(x/y)=2} \atop {x-10y=900}} \right. [/latex] [latex] \left \{ {{x/y=100} \atop {x-10y=900}} \right. [/latex] [latex] \left \{ {{x=100y} \atop {x-10y=900}} \right. [/latex] 100y-10y=900 90y=900 y=10 x=1000 2) [latex] \left \{ {{lg(x/y)=7} \atop {lg(xy)=5}} \right. [/latex] [latex] \left \{ {{x/y=7} \atop {xy=5}} \right. [/latex] [latex] \left \{ {{x=7y} \atop {xy=5}} \right. [/latex] 7y^2=5 y^2=5/7 y=+-\sqrt{5/7} y1=sqrt(5/7), x1=7sqrt(5/7) y2=-sqrt(5/7), x2=-7sqrt(5/7)