Question

3x-5y=4 9x-2y=7 .Solve by elimination method. ​

Answer 1

Explanation:

3x-5y=4

3x= 4+5y

x = (4+5y)÷3

Hence, in 9x-2y=7

9[(4+5y)÷3] - 2y = 7

(36÷3) + (45y÷3) - 2y = 7

12 +15y -2y = 7

12 + 13y = 7

13y = 7-12 = -5

y = -5/13

Answer 2

Explanation:

$9x - 2y = 7 \: \\ 3x - 5y = 4 \\3 (3x - 5y) = 3 \times 4 = 12 \\ 9x - 15y = 12 \\ (9x - 15y) - (9x - 2y) = 12 - 7 = 5 \\ 9x - 15y - 9x + 2y = - 13y = 5 \\ y = 5 \div - 13 = - \frac{5}{13} \\ 3x - 5y = 3x = 4 + 5y \\ = 4 + 5 \times \frac{ - 5}{13} = 4 - \frac{25}{13} \\ = \frac{4 \times 13 - 25 \times 4}{13 \times 4} = \frac{ - 12}{13}$