Question

Помогите пожалуйста срочно.
решить способом подстановки примеры: x+5y=7 , y+2x=11 , x-3y=17
3x-2y=4 5x-4y=8 x-2y=-13
Заранее спасибо!

Answer 1

Ответ:

Вот решение!)

Объяснение:

1)у+2х=11; 3)3х-2у=4; 5)х-2у==-13:

0+2х=11;. 3х=4+2у; х=-13+2у;

2х=11;. х=3/4+2/3у; х=-13+2у, у ЄR

х=11/2. х=3/4+2/3у, у Є R.

2)х+3у=17; 4)5х-4у=8;

х=17–3у; 5х=8+4у;

х=17-3у, уЄR. х=8/5+4/5у;

х=8/5+4/5у, у Є R.

Answer 2

$1)\ \ \left\{\begin{array}{l}x+5y=7\\y+2x=11\end{array}\right\ \ \left\{\begin{array}{l}x=7-5y\\y+2(7-5y)=11\end{array}\right\ \ \left\{\begin{array}{l}x=7-5y\\-9y=-3\end{array}\right\\\\\\\left\{\begin{array}{l}x=\dfrac{16}{3}\\y=\dfrac{1}{3}\end{array}\right\ \ \left\{\begin{array}{l}x=5\dfrac{1}{3}\\y=\dfrac{1}{3}\end{array}\right\ \ \ \ Otvet:\ \ (\, 5\dfrac{1}{3}\, ;\, \dfrac{1}{3}\, )\ .$

$2)\ \ \left\{\begin{array}{l}x-3y=17\\3x-2y=4\end{array}\right\ \ \left\{\begin{array}{l}x=17+3y\\3(17+3y)-2y=4\end{array}\right\ \ \left\{\begin{array}{l}x=17+3y\\7y=-47\end{array}\right\\\\\\\left\{\begin{array}{l}z=17+3y\\y=-\dfrac{47}{7}\end{array}\right\ \ \left\{\begin{array}{l}x=17-\dfrac{3\cdot 47}{7}\\y=\dfrac{47}{7}\end{array}\right\ \ \left\{\begin{array}{l}x=-\dfrac{22}{7}\\\ y=-\dfrac{47}{7}\end{array}\right\ \ \ Otvet:\ \ (\, -3\dfrac{1}{7}\ ;\ -6\dfrac{5}{7}\, )$

$3)\ \ \left\{\begin{array}{l}5x-4y=8\\x-2y=-13\end{array}\right\ \ \left\{\begin{array}{l}5(2y-13)-4y=8\\x=2y-13\end{array}\right\ \ \left\{\begin{array}{l}6y=73\\x=2y-13\end{array}\right\\\\\\\left\{\begin{array}{l}y=\dfrac{73}{6}\\\, x=\dfrac{68}{6}\end{array}\right\ \ \left\{\begin{array}{l}y=7\dfrac{1}{6}\\x=11\dfrac{1}{3}\end{array}\right\ \ \ Otvet:\ \ (\, 11\dfrac{1}{3}\, ;\, 7\dfrac{1}{6}\, )\ .$