Question

{х-у=3 {-х-4у=7решите систему уравнений​

Answer 1

Ответ:

х-у=3

-х-4у=7

х=3+у

-3-у-4у=7

-у-4у=7+3

-5у=10

у=-2

Answer 2

вроде так... ...................

Answer 3

To solve the system of equations:

1. х - у = 3
2. -х - 4у = 7

We can use the method of substitution or elimination. Let's use the method of elimination.

We'll multiply equation (1) by -1 and rewrite it as:

-х + у = -3

Now, we'll add equation (2) and the modified equation (1):

(-х - 4у) + (-х + у) = 7 + (-3)

Simplifying the equation:

-2х - 3у = 4

Now we have a new equation:

-2х - 3у = 4 --------(3)

Now we have a system of two equations:

-2х - 3у = 4 --------(3) -х - 4у = 7 --------(2)

To eliminate x, let's multiply equation (2) by -2 and equation (3) by -1:

2(-х - 4у) = 2(7) -1(-2х - 3у) = -1(4)

Simplifying the equations:

2х + 8у = -14 --------(4) 2х + 3у = -4 --------(5)

Now, we can subtract equation (5) from equation (4):

(2х + 8у) - (2х + 3у) = -14 - (-4)

Simplifying the equation:

5у = -10

Dividing both sides by 5:

у = -2

Now we can substitute the value of у into either equation (1) or (2). Let's use equation (1):

х - (-2) = 3 х + 2 = 3 х = 3 - 2 х = 1

Therefore, the solution to the system of equations is х = 1 and у = -2.