Question

СРОЧНО!!!!!!!
А) Решите систему способом подстановки
{х+3у=4
{5х+3у=32
Б) Решите систему способом сложения
{5х-3у=21
{8х+3у=18

Answer 1

$\displaystyle 1)\left \{ {{x+3y=4} \atop {5x+3y=32}} \right. \\\\\left \{ {{3y=4-x} \atop {5x+3y=32}} \right. \\\\5x+4-x=32\\x=7\\5*7+3y=32\\y=-1\\(x,y)=(7,-1)\\\\2)\left \{ {{5x-3y=21} \atop {8x+3y=18}} \right. \\\\(5x-3y)+(8x+3y)=21+18\\13x=39\\x=3\\5*3-3y=21\\y=-2\\(x,y)=(3,-2)$

Answer 2

Ответ:

a)

{х+3у=4

{5х+3у=32

3y=4-x

5x+3x=32

5x+4-x=32

x=7

5×7+3y=32

y=-1