Question

Решити 2х+3у=9 / 4х+3у=27 спосбом соложения 2) 2х+3у=2 / -2х+5у=-18 3) х+4у=39 / 2х-у=15

Answer 1

2х+3х=9
1)2+3=5
2)9-5=4
3)х=4
Я тебе другие ответы потом напишу,подожди.

Answer 2

To solve the systems of equations using the method of addition (also known as the method of elimination), follow these steps:

1. 2x + 3y = 9 4x + 3y = 27

We want to eliminate one variable by adding the two equations together. We'll start by making the coefficients of y in both equations the same so that when we add them, the y term cancels out. To do this, multiply the first equation by -1:

-1 * (2x + 3y) = -1 * 9 -2x - 3y = -9

Now the equations are:

-2x - 3y = -9 4x + 3y = 27

Now add the two equations:

(-2x - 3y) + (4x + 3y) = -9 + 27 2x = 18

Divide both sides by 2 to solve for x:

x = 18 / 2 x = 9

Now, substitute the value of x back into one of the original equations to solve for y. Let's use the first equation:

2x + 3y = 9 2 * 9 + 3y = 9 18 + 3y = 9

Subtract 18 from both sides:

3y = 9 - 18 3y = -9

Divide both sides by 3 to solve for y:

y = -9 / 3 y = -3

The solution to the first system of equations is x = 9 and y = -3.

2. 2x + 3y = 2 -2x + 5y = -18

Since the x-coefficients are negatives of each other, we can directly add the two equations to eliminate x:

(2x + 3y) + (-2x + 5y) = 2 - 18 3y + 5y = -16 8y = -16

Divide both sides by 8 to solve for y:

y = -16 / 8 y = -2

Now, substitute the value of y back into one of the original equations to solve for x. Let's use the first equation:

2x + 3y = 2 2x + 3(-2) = 2 2x - 6 = 2

Add 6 to both sides:

2x = 2 + 6 2x = 8

Divide both sides by 2 to solve for x:

x = 8 / 2 x = 4

The solution to the second system of equations is x = 4 and y = -2.

3. x + 4y = 39 2x - y = 15

In this case, we don't need to make any adjustments to the equations since there is already a variable with opposite coefficients (y and -y). We can directly add the two equations to eliminate y:

(x + 4y) + (2x - y) = 39 + 15 3x + 3y = 54

Now, divide both sides by 3 to solve for x:

x + y = 18

Now, we have an equation with both x and y, but we don't have enough information to find the exact values of x and y separately. However, if you have more information or another equation to work with, you may be able to find the specific values of x and y. As it stands, the solution to the third system of equations is x + y = 18.