Question

Решите 4 примера из прикреплённого файла

Answer 1

Объяснение:

все написано на листочку

Answer 2

1. $\left \{ {{x-3y=4} \atop {2x-y=3}} \right.$$\left \{ {{x=4+3y} \atop {2x-y=3}} \right.$$\left \{ {{1-3(-1)=4} \atop {2*1-(-1)=3}} \right.$$\left \{ {{4=4} \atop {3=3}} \right.$

    2(4+3y)-y=3

    y=-1

    x=4+3(-1)

    x=1

    (x; y)=(1; -1)

2. $\left \{ {{4x-y=1} \atop {5x+3y=14}} \right.$$\left \{ {{y=-1+4x} \atop {5x+3y=14}} \right.$$\left \{ {{4*1-3=1} \atop {5*1+3*3=14}} \right.$$\left \{ {{1=1} \atop {14=14}} \right.$

    5x+3(-1+4x)=14

    x=1

    y=-1+4*1

    y=3

    (x; y)=(1;3)

3. $\left \{ {{7a+2b=9} \atop {3a+b=-1}} \right.$$\left \{ {{7a+2b=9} \atop {b=-1-3a}} \right. \left \{ {{7*11+2*(-34)=9} \atop {3*11-34=-1}} \right. \left \{ {{9=9} \atop {-1=-1}} \right.$

    7a+2(-1-3a)=9

    a=11

    b=-1-3*11

    b=-34

    (a; b)=(11; -34)

4. $\left \{ {{3x+4y=-2} \atop {6x-7y=11}} \right. \left \{ {{x=-\frac{2}{3}-\frac{4}{3}y} \atop {6x-7y=11}} \right. \left \{ {{3*\frac{2}{3}+4*(-1)=-2} \atop {6*\frac{2}{3}-7*(-1)=11 }} \right. \left \{ {{-2=-2} \atop {11=11}} \right.$

    6$(-\frac{2}{3} -\frac{4}{3} y)-7y=11$

   $y=-1\\x=-\frac{2}{3} -\frac{4}{3}*(-1)\\x=\frac{2}{3}$

    $(x; y)=(\frac{2}{3} ; -1)$