Question

Solve by cross-multiplication method

6x + 7y – 11 = 0, 5x + 2y = 13

Answer 1

6x + 7y – 11 = 0 → (1)

5x + 2y = 13 → (2)

Use the coefficient for cross multiplication

`x/(- 91 - (-22)) = y/(- 55 - (-78)) = 1/(12 - (35))`

`x/(- 91 + 22) = y/(-55 + 78) = 1/(12 - 35)`

`x/(-69) = y/23 = 1/(-23)`

But `x/(-69) = 1/(-23)`

– 23x = – 69

∴ 23x = 69

x = `69/23`

= 3

`y/23 = 1/(-23)`

– 23y = 23

23y = – 23

y = `- 23/23`

y = –1

∴ The value of x = 3 and y = –1