Question

Решать систему 15x+21y=3930x+44y=81​

Answer 1

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Answer 2

15x+21y=39

30x+44y=81​

х=13/5-7/5у

30х+44у=81

30(13/5-7/5у)+44у=81

у=3/2

х=13/5-7/5*3/2

х=1/2

(х,у)=(1/2,3/2)

15*1/2+21*3/2=39

30*1/2+44*3/2=81

39=39

81=81

(х,у)=(1/2,3/2)

Answer 3

To solve the system of equations:

15x + 21y = 39 30x + 44y = 81

There are multiple methods to solve this system, including substitution, elimination, or matrix methods. I will use the elimination method in this case.

First, let's multiply the first equation by 2 to eliminate the coefficient of x:

2(15x + 21y) = 2(39) 30x + 42y = 78

Now we can subtract the second equation from this new equation to eliminate x:

(30x + 42y) - (30x + 44y) = 78 - 81 30x + 42y - 30x - 44y = -3 -2y = -3

Dividing both sides of the equation by -2, we get:

y = (-3) / (-2) y = 3/2 y = 1.5

Now we can substitute this value of y back into either of the original equations. Let's use the first equation:

15x + 21(1.5) = 39 15x + 31.5 = 39 15x = 39 - 31.5 15x = 7.5

Dividing both sides of the equation by 15, we get:

x = 7.5 / 15 x = 0.5

Therefore, the solution to the system of equations is x = 0.5 and y = 1.5.