Question

Решите систему уравнений
4х – 9y = 3,
x+3y = 6.

Answer 1

{4x-9y=3

{x+3y=6. |*3→

{4x-9y=3

{3x+9y=18

__________

7x=21; x=21:7=3

__________

3+3y=6

3y=6-3

3y=3

y=3:3=1

Ответ: (3;1).

Answer 2

$\displaystyle\bf\\\left \{ {{4x-9y=3} \atop {x+3y=6} \ | \cdot 3} \right. \\\\\\+\left \{ {{4x-9y=3} \atop {3x+9y=18}} \right. \\---------\\7x=21\\\\x=3\\\\3y=6-x=6-3=3\\\\y=1\\\\Otvet:(3 \ ; \ 1)$