Question

X+5y=7 3x-2y=4 X=7-5y 7x-5y=4

Answer 1

Ответ:

x+5y=7

x=7-5y

5y=7-x

5y=7-7-5y

5y+5y=7-7

10y=0

y=0

x=7-5×0

x=7

3x-2y=4

3x=4+2y

-2y=4-3x из за знака - меняем все знаки

2y=-4+3x

2y=-4+3(4+2y)

2y=-4+12+6y

2y-6y=-4+12

-4y=8

4y=-8

y=2

3x=4-2×2

3x=0

x=0

x=7-5y

5y=7-x

5y=7-7-5y

10y=0

y=0

x=7

7x-5y=4

7x=4-5y

5y=4-7x

7x=4-4-7x

14x=0

x=0

5y=4-7×0

y=4/5

решал методом подстоновки

Answer 2

It looks like you've provided a system of equations:

1. $x + 5y = 7$
2. $3x - 2y = 4$
3. $x = 7 - 5y$
4. $7x - 5y = 4$

Let's see if we can solve this system step by step.

First, let's solve equations 1 and 3 for $x$:

From equation 1: $x = 7 - 5y$

From equation 3: $x = 7 - 5y$

These two equations are the same, which means that equations 1 and 3 represent the same line in the coordinate plane.

Now, let's use equations 2 and 4 to solve for $x$ and $y$:

Equation 2: $3x - 2y = 4$

Equation 4: $7x - 5y = 4$

Let's solve equation 2 for $x$:

$3x = 4 + 2y$ $x = \frac{4 + 2y}{3}$

Now we can substitute this value of $x$ into equation 4:

$7x - 5y = 4$ $7 \left(\frac{4 + 2y}{3}\right) - 5y = 4$

Now we can solve for $y$:

$7 \cdot \frac{4 + 2y}{3} - 5y = 4$ $\frac{28 + 14y}{3} - 5y = 4$

Multiply both sides by 3 to get rid of the fraction:

$28 + 14y - 15y = 12$ $-y = -16$ $y = 16$

Now that we have the value of $y$, we can substitute it back into equation 1 to find $x$:

$x + 5y = 7$ $x + 5 \cdot 16 = 7$ $x + 80 = 7$ $x = -73$

So, the solution to the system of equations is $x = -73$ and $y = 16$. Keep in mind that since equations 1 and 3 were the same, this system had redundant equations and the solution might not be consistent with the original equations.