Question

Rezolvati:
Prin metoda substitutiei:

x-2y=0
Acolada
4x+5y=26

Prin metoda reducerii:

4x-7y=30
Acolada
4x-5y=90

VA ROG AJUTATIMA CA AVEM INCURAND EVALUARE

Answer 1

$1)\left\{\begin{matrix}</p><p> x - 2y = 0& \\ </p><p> 4x + 5y = 26& </p><p>\end{matrix}\right.$

$x - 2y = 0 = > x = 2y$

$4x + 5y = 26$

$4 \times 2y + 5y = 26$

$8y + 5y = 26$

$13y = 26 \: | \div 13$

$y = 2$

$x = 2y = > x = 2 \times 2 = 4$

$2)\left\{\begin{matrix}</p><p> 4x - 7y = 30& \\ </p><p> 4x - 5y = 90 \: | \times ( - 1) & </p><p>\end{matrix}\right.$

$\left\{\begin{matrix}</p><p> 4x - 7y = 30& \\ </p><p> - 4x + 5y = - 90& </p><p>\end{matrix}\right.$

$- 2y = - 60 \: | \div ( - 2)$

$y = 30$

$4x - 7y = 30$

$4x - 7 \times 30 = 30$

$4x - 210 = 30$

$4x = 30 + 210$

$4x = 240 \: | \div 4$

$x = 60$