Question

1/X + 1/Y = 12
2/X - 1/Y = -1

tentukan 1/ X+Y

Answer 1

1/x + 1/y = 12
2/x - 1/y = -1
-------------------- (+)
3/x = 11
x = 3/11

substitusi x = 3/11 ke prsamaan :
1/x + 1/y = 12
1/(3/11) + 1/y = 12
11/3 + 1/y = 12
1/y = 12  -  11/3
1/y = (36 -  11)/3
1/y = 25/3
y = 3/25

maka nilai dari 1/(x+y) = 1/(3/11 + 3/25) = 1 / (75+33)/275 = 275/108