Question

Va rog e și f
e) {2(7x+y)-3(2x-y)=-1
2(2x-3y)+5y=-24

f){2(3x+2y)+2(-x-4y)=-12
2(5x+y)-4y=-14​

Answer 1

e)

$\left \{ {{14x+2y-6x+3y=-1} \atop {4x-6y+5y=-24}} \right.$    <=> $\left \{ {{8x+5y=-1} \atop {4x-y=-24}} \right.$    

=>-y=-24-4x

y=24+4x

8x+5y=-1

8x+5(24+4x)=-1

8x+120+20x=-1

28x=-121

x=-121/28

y=24+4*(-121/28)=(168-121)/7=47/7

f)

$\left \{ {{6x+4y-2x-8y=-12} \atop {10x+2y-4y=-14}} \right.$   <=>  $\left \{ {{4x-4y=-12} \atop {10x-2y=-14}} \right.$   <=> $\left \{ {{x-y=-3} \atop {5x-y=-7}} \right.$

x=y-3

5x-y=-7

5(y-3)-y=-7

5y-15-y=-7

4y=8

y=2

x=y-3

x=2-3

y=-1