Question

Система 4x - y = 9 3x + 7y = -1

Answer 1

Ответ:

Смотри решение на фото..

Answer 2

Ответ:

4х + у =9

у=9-4

у=5

_________

4+ 5=9

9=9

Answer 3

To solve the system of linear equations:

1. $4x - y = 9$
2. $3x + 7y = -1$

We can use either the substitution method or the elimination method. Let's use the elimination method to eliminate one of the variables:

First, let's multiply the second equation by $1$ and the first equation by $7$ to eliminate $y$:

1. $4x - y = 9$ (Equation 1)
2. $21x + 49y = -7$ (Multiply the second equation by $7$) (Equation 2)

Now, let's subtract Equation 1 from Equation 2 to eliminate $y$:

$21x + 49y - (4x - y) = -7 - 9$ $21x + 49y - 4x + y = -16$ $17x + 50y = -16$ (Equation 3)

Next, let's solve for $y$ in Equation 3:

$50y = -16 - 17x$ $y = \frac{-17x - 16}{50}$ (Equation 4)

Now, let's substitute the value of $y$ from Equation 4 into Equation 1:

$4x - \frac{-17x - 16}{50} = 9$

Now, we can solve for $x$:

$4x + \frac{17x + 16}{50} = 9$

Multiply both sides by $50$ to eliminate the fraction:

$200x + 17x + 16 = 450$ $217x = 434$

Now, divide both sides by $217$ to find $x$:

$x = \frac{434}{217}$ $x = 2$

Now that we have $x$, let's substitute this value into Equation 1 to find $y$:

$4(2) - y = 9$ $8 - y = 9$ $-y = 1$ $y = -1$

So, the solutions for the system of equations are $x = 2$ and $y = -1$.