# Thread: solve using the multiplication principle

1. ## solve using the multiplication principle

solve using the multiplication principle:

-7x > 1/15 (yes that is a fraction and that is what is confusing me)

2. I'm not too sure what the multiplication principle is, but does it refer to cross-mutiplying?

i.e.

$\displaystyle \frac{-7x}{1}>\frac{1}{15}$

$\displaystyle -105x>1$ (from cross-multiplying)

$\displaystyle x<-\frac{1}{105}$

Sorry if I misunderstood the question.

3. Yea I got that too. Doesn't seem anything complicated about it.. lol

4. Originally Posted by bball20
solve using the multiplication principle:

-7x > 1/15 (yes that is a fraction and that is what is confusing me)
Multiply by the reciprocal of negative 7. I believe the 'priciple' in question is the fact that $\displaystyle a<b\Rightarrow{-a}>-b$

So

$\displaystyle \frac{-1}{7}(-7x)<\left(\frac{1}{15}\right)\frac{-1}{7}$

5. -7x > 1/15

-7x ( 15 ) > 1

-105x > 1

x < -1/105

6. ## A little problem

Hi,

My name is Paul and I'm in class 5...sorry 'cuz I posted in this thread but...something is entangling me...sorry if I'm writing wrong 'cuz I'm from Romania...I don't know if this is harmonize with the thread but...1x2x3x...x20...how to resolve???
If can someone help me

THANKS!!!

7. Create a new thread, please ...
By the way, what do you mean by "resolve" ? The expression you just gave us is the factorial of $\displaystyle 20$, written $\displaystyle 20!$. Most calculators have a factorial key to compute it quickly. This way, $\displaystyle 20! = 2432902008176640000$.