# Problem - Solve Two Ways

#### TheJason

Staff member
Moderator
Isolate l.

$$\displaystyle \dfrac{8 + k}{m} = \dfrac{1}{l}$$

#### MarkFL

##### La Villa Strangiato
Staff member
Moderator
Math Helper
a) Invert both sides to obtain:

$$\displaystyle l=\frac{m}{k+8}$$

b) Cross multiply to obtain:

$$\displaystyle l(k+8)=m$$

Divide through by $$k+8$$:

$$\displaystyle l=\frac{m}{k+8}$$

harpazo

#### harpazo

##### Pure Mathematics
Banned
a) Invert both sides to obtain:

$$\displaystyle l=\frac{m}{k+8}$$

b) Cross multiply to obtain:

$$\displaystyle l(k+8)=m$$

Divide through by $$k+8$$:

$$\displaystyle l=\frac{m}{k+8}$$
You know all the tricks.

#### TheJason

Staff member
Moderator
Who are we kidding here? Of course, inverting is the easiest - but the other way isn't much harder.

#### harpazo

##### Pure Mathematics
Banned
Who are we kidding here? Of course, inverting is the easiest - but the other way isn't much harder.
Why do you talk to Mark this way? Are YOU kidding me???????

#### TheJason

Staff member
Moderator
Why do you talk to Mark this way? Are YOU kidding me???????
He should smack me!

#### MarkFL

##### La Villa Strangiato
Staff member
Moderator
Math Helper
I didn't feel there was anything bad or disrespectful about that post. Inverting was a one step process. It was very simple going that route.

TheJason

#### TheJason

Staff member
Moderator
There was no disrespect aimed at Mark. I was looking at the solution itself, apart from Mark suggesting it. Anyway, I knew the answers beforehand, but I posted the problem to see if other people knew.

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#### harpazo

##### Pure Mathematics
Banned
There was no disrespect aimed at Mark. I was looking at the solution itself, apart from Mark suggesting it. Anyway, I knew the answers beforehand, but I posted the problem to see if other people knew.
Your choice for words is the problem. Read your post again. I am talking about the words "of course." Example, if I walk into a dentist office and the doctor tells me that I have two cavities and I reply OF COURSE I KNOW WHAT A CAVITY IS, DOCTOR. This is a disrespectful reply.

It does not matter if I know what a cavity is. I do not know what a cavity is at the level of a dentist. You and I know basic math but Mark is a doctor of math compared to what we know about the subject. Understand? I'm sure you do not understand.