# problem with numbers

• May 23rd 2008, 06:52 AM
recca
problem with numbers
For which numbers N, is N*-2 greater than -2? In other words, for which numbers N, is N*-2>-2?
Investigate theis question as follow:

A) Without using a calculator, multiply -2 by the given numbers. Show your work. In each case, determine wheather the resulting product is greater than -2 or not.

3.15, ,1.01, 0.85, 0.002, -0.3, -4.2
4 3/5, 1 2/3, 9/10, 3/5, -7/8, -1 1/8

B) Based on your answers in part a and on th emeaning and rules of multiplication, describe the collection of all numbers N, for which N8-2 is greater than -2.

Thank you
• May 23rd 2008, 12:57 PM
masters
Well, nobody seems to want to respond to this one, so here goes.

In order for $N\cdot-2>-2$,

$N<1$

For instance; if $N=\frac{1}{2}$, then $\frac{1}{2}\cdot-2=-1$ which is greater than -2.

If $N=-2$, then $-2\cdot-2=2$, which is greater than -2.

So, there you go.

I assume you can multiply -2 times all your sample numbers and compare the products to see if any are greater than -2.

You'll find that 0.85, 0.002, -0.3, -4.2, $\frac{9}{10} , \frac{3}{5} , \frac{-7}{8} and -1\frac{1}{8} \$, all conform to the fact that N < 1 is the set of numbers that satisfy your original statement.
• May 23rd 2008, 01:25 PM
recca
Thank you so much!