Помогите, пожалуйста, решить системы уравнений СПОСОБОМ СЛОЖЕНИЯ.
1) x - 2y =8
2x +3y =9
2) x + 2y = -2
3x - y = 8
3) 2x +3y = -7
x-y = 4
4) x - 4y = -1
3x - y =4
5) x - 6y = -2
2x + 3y = 11
6) 2x + 3y = 1
6x - 2y = 14
1) x - 2y =8
2x +3y =9
2) x + 2y = -2
3x - y = 8
3) 2x +3y = -7
x-y = 4
4) x - 4y = -1
3x - y =4
5) x - 6y = -2
2x + 3y = 11
6) 2x + 3y = 1
6x - 2y = 14
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Answers & Comments
1) x - 2y =8 2x-4y=16
2x +3y =9 ⇒ 2x +3y =9 7y=-7 y=-1 x=-2+8=6
проверка
6-2·(-1)=8
2·6+3·(-1)=9 верно
2) x + 2y = -2 x+2y=-2
3x - y = 8 6x-2y=16 ⇒ 7x=14 x=2 y=3·2-8=-2
проверка
2+2·(-2)=-2
3·2-(-2)=8 верно
3) 2x +3y = -7 2x+3y=-7
x-y = 4 ⇒ 2x-2y=8 ⇒ -5y=15 y= -3 x=4+(-3)=1
проверка
2·1+3·(-3)=-7
1-(-3)=4 верно
4) x - 4y = -1 3x-12y=-3
3x - y =4 3x-y=4 11y=7 y=7/11 x= -1+4·7/11=17/11
проверка
17/11-4·7/11= -1
3·17/11-7/11 =4 верно
5) x - 6y = -2 2x-12y=-4
2x + 3y = 11 2x+3y=11 15y=15 y=1 x=6·1-2=4
проверка
4-6·1=-2
2·4+3·1=11 верно
6) 2x + 3y = 1 6x+9y=3
6x - 2y = 14 ⇒ 6x - 2y = 14 11y= -11 y= -1 x=(1-3·(-1))/2=2
проверка
2·2+3·(-1)=1
6·(2)-2·(-1)=14 верно
Verified answer
1)y=1X=2
2)y=2
x=-6
4)y=7/11