Question

resolva os sistemas a seguir 3x+3y=21
2×-5y=9​

Answer 1

3x + 3y = 21        *(5)

2x - 5y = 9          *(3)

15x + 15y = 105

6x - 15y = 27

21x = 132

x = 132/21

x = 44/7

3x + 3y = 21

3(44/7) + 3y = 21

132/7 + 3y = 21

132/7 + 21y/7 = 147/7

132 + 21y = 147

21y = 147 - 132

21y = 15

y = 15/21

y = 5/7

Resposta: ( 44/7,  5/7 ).