Question

21x - 20 y = -16,9x - 10y = 1.​

Answer 1

Ответ:

(-6;-5.5)

Пошаговое объяснение:

Если это система то решается так:

21х-20у=-16

9х-10у=1 умножу на 2

21х-20у=-16

18х-20у=2 вычту

21х-18х-20у-(-20у)=-16-2

3х-20у+20у=-18

3х=-18

х=-6

9х-10у=1

Выражу от сюда у:

у=(9х-1)/10

у=(9*(-6)-1)/10=(-54-1)/10=-55/10=-5.5

Answer 2

Ответ:

Пошаговое объяснение:

Если это система то решается так:

21х-20у=-16

9х-10у=1 умножу на 2

21х-20у=-16

18х-20у=2 вычту

21х-18х-20у-(-20у)=-16-2

3х-20у+20у=-18

3х=-18

х=-6

9х-10у=1

Выражу от сюда у:

у=(9х-1)/10

у=(9*(-6)-1)/10=(-54-1)/10=-55/10=-5.5

Answer 3

To solve the system of linear equations

$\begin{cases} 21x - 20y = -16 \\ 9x - 10y = 1 \end{cases}$

we can use either the substitution method or the elimination method. Here, I will demonstrate how to use the elimination method.

First, let's multiply the second equation by 2 to make the coefficients of $y$ in both equations equal.

$18x - 20y = 2$

Now the system becomes:

$\begin{cases} 21x - 20y = -16 \\ 18x - 20y = 2 \end{cases}$

We subtract the second equation from the first:

$(21x - 18x) - (20y - 20y) = -16 - 2$

Simplifying this, we get:

$3x = -18$

Solving for $x$:

$x = \frac{-18}{3} = -6$

Now that we have $x = -6$, we can substitute this value into one of the original equations to find $y$. Let's use the second equation:

$9x - 10y = 1$

Plugging in $x = -6$:

$9(-6) - 10y = 1$

$-54 - 10y = 1$

Solving for $y$:

$-10y = 1 + 54$

$-10y = 55$

$y = \frac{55}{-10} = -\frac{11}{2}$

So the solution to the system of equations is $x = -6$ and $y = -\frac{11}{2}$.