penyelesaian dari sistem persamaan 6/x+3/y=33 ; 3/x-4/y = -11 adalah a dan b. nilai dari 15ab adalah...

jawab

misal  1/x = m , 1/y = n
6/x + 3/y = 33 → 6m+ 3n = 33
atau  2m + n = 11 ..(i)

3/x - 4/y = -11 → 3m - 4n = - 11 ...(ii)

(i dan ii)
2m + n = 11 ...} kali 3
3m - 4n = -11..} kali 2

6m+ 3n = 33
6m - 8n = - 22 ...|| (-)
11 n = 55
n = 5

2m + n  = 11
2m + 5 = 11
2m= 6
m = 3

1/x = m→ x = 1/m = 1/3
1/y =n→ y = 1/n = 1/5

a = x = 1/3
b = y = 1/5

nilai 15 ab  = 15 (1/3)(1/5)
15 ab = 1