Question

Solve for x in the proportion:

Answer 1

\[\frac{ x }{ x + 12 }\] = \[\frac{ 1 }{ x - 1 }\]

Answer 2

@Luigi0210

Answer 3

So you would first cross multiply

Answer 4

@johnweldon1993 's got you brah

Answer 5

x + 12 = 2x - 1

Answer 6

Not quite....remember

x * x = x²

try that 1 more time

Answer 7

x + 12 = x^2 - 1 :P

Answer 8

Try again >.>

Answer 9

Closer

x(x -1)

x * x = ?
x * -1 = ?

Answer 10

x + 12 = x^2 - x?

Answer 11

There we go...

Okay ...next step is to combine like terms

Answer 12

cancel out x on each side?o;

Answer 13

Right....lets subtract an 'x' from each side...what do we get when we do that?

Answer 14

12 = x^2 - 2x?

Answer 15

Right....now that would be annoying to solve....so now lets subtract 12 from both sides...

x² - 2x - 12 = 0

Look enough like a quadratic?

Answer 16

Yes.

Answer 17

So now lets use the quadratic formula to solve...

\[\large \frac{ -b \pm \sqrt{b^2 - 4ac} }{ 2a }\]

Using

a = 1
b = -2
c = -12

Can you do that?

Answer 18

Let me plug it in. gimme a sec.

Answer 19

Take your time :P

Answer 20

\[ \frac{ 2 \pm \sqrt{52}}{ 2 }\]

Answer 21

Perfect

so now

you will have 2 answers *notice the +/- sign

2 equations you need to solve are

\[\large \frac{ 2 + \sqrt{52} }{ 2 }\]
and
\[\large \frac{ 2 - \sqrt{52} }{ 2 }\]

Answer 22

9.21 / 2 -7.21/2

Answer 23

\[\approx \]

Answer 24

ops i meant -5.21 :p

Answer 25

Ahh there you go...lol I was going to say hmm not quite....

but yes

9.21 / 2

and

-5.21 / 2

These will be your *approximate* answers for 'x'

Answer 26

I got it (: Thank you!

Answer 27

No problem!