Question

1/3+1/4=1/x

Answer 1

What is the LCD of all denominators?

Answer 2

12 right?

Answer 3

i got to 7/12=1/x but that was as far as i could get

Answer 4

For the numbers 3 and 4, it is 12.
But remember there is also an x in a denominator.
You need the LCD of all denominators including the denominator of x.

Answer 5

oh then i really am lost, ho would you find that?

Answer 6

OK. Let me put my explanation on hold for a minute.

Answer 7

Since you already used the LCD of 3 and 4, which is 12, to add the fractions, you are correct so far.

Answer 8

You have

\(\dfrac{7}{12} = \dfrac{1}{x} \)

Now you can cross multiply.

Answer 9

so itd be 12/7?

Answer 10

Correct.

Answer 11

what would x be 7?

Answer 12

Check:

\(\large \dfrac{1}{3} + \dfrac{1}{4} = \dfrac{1}{x} \)

\(\large\dfrac{1}{3} + \dfrac{1}{4} = \dfrac{1}{\frac{12}{7}} \)

\(\dfrac{7}{12} = \dfrac{7}{12} \)

That means solution x = 12/7 is correct.