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18 votes
Solve the system: 10x-9y=8 21y+15x=0.5

PLEASE HELP NEED ASAP

User Trystuff
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2 Answers

10 votes
10 votes

Final answer:

To solve the provided system of linear equations, the elimination method is used to first find the value of y, and then substitute this value back into an original equation to find x. The solution is x = 1/2 and y = -1/3.

Step-by-step explanation:

To solve the system of equations, we can use either the substitution method or the elimination method. In this case, the elimination method may be more straightforward. We have the following equations:

  • 10x - 9y = 8
  • 21y + 15x = 0.5

To eliminate one of the variables, multiply the first equation by 15 and the second equation by 10, so the coefficients of x will be equal.

  • (15)(10x - 9y) = (15)(8)
  • (10)(21y + 15x) = (10)(0.5)

Distribute and get:

  • 150x - 135y = 120
  • 210y + 150x = 5

Now we subtract the second equation from the first:

  • (150x - 135y) - (210y + 150x) = 120 - 5
  • -345y = 115

Then, solve for y:

y = -115 / 345

y = -1/3

Now that we have y, substitute it back into one of the original equations to find x:

10x - 9(-1/3) = 8

10x + 3 = 8

x = 5 / 10

x = 1/2

Therefore, the solution to the system is x = 1/2 and y = -1/3.

User Panayiotis
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2.8k points
23 votes
23 votes

Answer:

x = 1/2

y = -1/3

Step-by-step explanation:

10x - 9y = 8 (Multiply by 3)

15x + 21y = 0.5 (Multiply by -2)

30x - 27y = 24

-30x - 42y = -1

-69y = 23

y = -1/3

10x - 9y = 8

10x - 9(-1/3) = 8

10x + 3 = 8

10x = 5

x = 1/2

User Lavasia
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2.7k points