Solving systems of equation using elimination?

Question

-5x+2y=-10
3x-6y=-18

7x-4y=-3
2x+5y=-7

3x+2y=-2
5x+2y=10

3x-6y=4
-x+2y=-5

thank you for your time and help. I do not understand these at all

Answer 1

Elimination method  :

7x - 4y = -3    -(1)

2x + 5y = -7   -(2)

Multiply each side by 5 to the equation (1) and Multiply each side by 4 to the equation (2)

35x - 20y = -15 (3)and

8x + 20y = -28  (4)

Add (3) and (4)

43x = -43

x = -1

Multiply each side by 2 to the equation (1) and Multiply each side by 7 to the equation (2)

14x - 8y = -6       -(5)

14x + 35y = -49   -(6)

Subtract (5) from (6)

-43y = 43

y = -1

 

 

 

 

 

 

 

Answer 2

Elimination method  :

-5x + 2y = -10    -(1)

3x - 6y = -18      -(2)

Multiply each side by 3 to the equation (1) and Multiply each side by 5 to the equation (2)

-15x + 6y = -30   (3) and

15x - 30y = -90   (4)

Add (3) and (4)

-24y = -120

y = 5

Multiply each side by 6 to the equation (1) and Multiply each side by 2 to the equation (2)

-30x +12y = -60       -(5)

6x - 12y = -36   -(6)

Add  (5)  to (6)

-24x = -96

x = 4.

Answer 3

Elimination method  :

3x + 2y = -2    -(1)

5x + 2y = 10   -(2)

Multiply each side by 5 to the equation (1) and Multiply each side by 3 to the equation (2)

15x +10y = -10   (3) and

15x + 6y = 30   (4)

Subtract  (4) from  (3)

4y = -40

y = -10

Subtract (2) from (1)

-2x = -12

x = 6.

Answer 4

Elimination method  :

3x - 6y = 4          -(1)

-x + 2y = - 5      -(2)

The two equation slopes are equal and

The equation (1) and the equation (2) are parallel

So they have no solution.