-8x + 5y = 18 and 7x + 6y = 5 What does x= and what does y=?

Answer 1

-8x+5y = 18 -> -48x + 30y = 108 (1)
7x + 6y = 5 -> 35x + 30y = 25 (2)
(1) - (2) = -48x - 35 x = 108 -25 -> -83x = 83 -> x=-1
-8*-1 + 5y = 18 -> y=2

Answer 2

- 8x + 5y = 18- - - - - -Equation 1
7x + 6y = 5- - - - - - -- Equation 2
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Multiply equation 1 by - 6 and equation 2 by 5

- 8x + 5y = 18

- 6(- 8) + (- 6)(5y) = - 6(18)

48 + (- 30y) = - 108

48 - 30y = - 108

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7x + 6y = 5

5(7x) + 5(6y) = 5(5)

35x + 30y = 25

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48 x - 30y = - 108
35x + 30y= 25
- - - - - - - - - - - -

83x = - 83

83x / 83 = - 83 / 83

x = - 83 / 83

x = - 1

Insert the x value into equaion 1

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- 8x + 5y = 18

- 8( - 1) + 5y = 18

8 + 5y = 18

8 + 5y - 8 = 18 - 8

5y = 10

5y / 5 = 10/ 5

y = 10 / 5

y = 2

Insert the y value into euation 1

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Check for equation 1

- 8x + 5y = 18

- 8(- 1) + 5(2) = 18

8 + 10 = 18

18 = 18

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Check for equation 2

7x + 6y = 5

7(- 1) + 6(2) = 5

- 7 + 12 = 5

5 = 5

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The solution set is { -1, 2 }

- - - - - - - - - - s-

Answer 3

-8x + 5y = 18
7x + 6y = 5
Multiply the top by y and the bottom by 8:
-56 x + 35 y = 126
56 x + 48y = 40
Now add to isolate y:
83 y = 156 or y = 166/83 = 2
Now that you have y, put it in the bottom equation and solve for x:
7x + 6(2) = 5
7x = 5 - 12 = -7 and x = -1

Answer 4

x = -1
y = 2

Answer 5

x= -1, y=2

Answer 6

One quick way is to multiply the first equation by the factor of x in the second, then multiply the second by the factor of x in the first:

multiply the first by 7:

-56x +35y = 126

multiply the second by -8:

-56x -48y = -40

then change the sign in one of them (let us say the second one) and "add them up":


-56x +35y = 126
+56x +48y = +40
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0x +83y = 166

then y = 2

Go back and substitute y=2 in any of the equations (better: d both to make sure you get the same value for x)

Answer 7

That is immposible to answer because it has two unknown variables and not enough to rule on out