can some one help me with this math problem?

0 ⤊

can some one help me with this math problem?

x+y=28
xy=7
find 1/x+1/y

note: x value is the same through out the whole problem and so is the y value

2007-10-13 10:21:53 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics

2 answers

1/x+1/y = (x+y)/(xy) = 28/7 = 4

2007-10-13 10:27:33 · answer #1 · answered by ironduke8159 7 · 0⤊ 0⤋

Rearranging the second equation gives
y = 7/x and x = 7/y
If we substitue these back into the first equation
7/y + 7/x = 28
Now divide both sides by 7
1/x + 1/y = 4

2007-10-13 17:29:55 · answer #2 · answered by jestephen 2 · 0⤊ 0⤋