Question

Solve each pair of simultaneous equations giving both solutions. You need to multiply both equations by suitable numbers before adding \subtracting to eliminate.
a) 6x - 7y = 9
3x + 2y = 54

b) 4x - 5y = 12
2x - 3y = 8


c) 4x - 2y = 28
3x + 3y = 12
please work it out and clear. who ever answer give them brainlest answer​

Answer 1

Answer:

a) x = 12  y = 9

b) x = -2   y = -4

c) x = 6   y = -2

Step-by-step explanation:

a)

Equation 1:  6x - 7y = 9

Equation 2:  3x + 2y = 54

Multiply Equation 2 by 2:

⇒ 6x + 4y = 108

Subtract equations:

   6x + 4y = 108

-    6x - 7y = 9      

           11y = 99

Divide both sides by 11:

⇒ y = 9

Substitute found value of y into Equation 1 and solve for x:

⇒ 6x - 7(9) = 9

⇒ 6x - 63 = 9

⇒ 6x = 72

⇒ x = 12

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b)

Equation 1:  4x - 5y = 12

Equation 2:  2x - 3y = 8

Multiply Equation 2 by 2:

⇒ 4x - 6y = 16

Subtract equations:

   4x - 6y = 16

-   4x - 5y = 12      

           -y = 4

Divide both sides by -1:

⇒ y = -4

Substitute found value of y into Equation 1 and solve for x:

⇒ 4x - 5(-4) = 12

⇒ 4x + 20 = 12

⇒ 4x = -8

⇒ x = -2

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c)

Equation 1:  4x - 2y = 28

Equation 2:  3x + 3y = 12

Multiply Equation 1 by 3:

⇒ 12x - 6y = 84

Multiply Equation 2 by 4:

⇒ 12x + 12y = 48

Subtract equations:

     12x - 6y = 84

-   12x + 12y = 48  

            -18y = 36

Divide both sides by -18:

⇒ y = -2

Substitute found value of y into Equation 1 and solve for x:

⇒ 4x - 2(-2) = 28

⇒ 4x + 4 = 28

⇒ 4x = 24

⇒ x = 6