## Rangpur Higher Secondary 2011/3

Problem for Higher Secondary Group from Divisional Mathematical Olympiad will be solved here.
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BdMO
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### Rangpur Higher Secondary 2011/3

Problem 3:
If \$-3<f<4\$ and \$-2<g<1\$, then what is the range of possible values of \$fg\$?

leonardo shawon
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Location: Dhaka

### Re: Rangpur Higher Secondary 2011/3

its \$6<fg<4\$
i did this way,, i multiple the upper limit and lower limit of f and g.
Ibtehaz Shawon
BRAC University.

long way to go .....

Mehfuj Zahir
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### Re: Rangpur Higher Secondary 2011/3

THE INTERVAL OF fg should be [-8,6]
Last edited by Mehfuj Zahir on Thu Feb 03, 2011 2:38 am, edited 1 time in total.

leonardo shawon
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Location: Dhaka

### Re: Rangpur Higher Secondary 2011/3

\$-3<f<1\$ and \$-2<g<4\$
if \$f=-2.90\$ and \$g=-1.90\$ their multiple \$fg\$ will give a positive answer!!!
thats why \$6<fg<4\$
Ibtehaz Shawon
BRAC University.

long way to go .....

Mehfuj Zahir
Posts: 78
Joined: Thu Jan 20, 2011 10:46 am

### Re: Rangpur Higher Secondary 2011/3

if one of them is negative then?first time i was wrong the ans is (-8,6)

*Mahi*
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### Re: Rangpur Higher Secondary 2011/3

leonardo shawon wrote:\$-3<f<1\$ and \$-2<g<4\$
if \$f=-2.90\$ and \$g=-1.90\$ their multiple \$fg\$ will give a positive answer!!!
thats why \$6<fg<4\$
It's two ranges of \$f\$ and \$g\$ .It doesn't mean that if \$f\$ is \$-3\$ then \$g\$ is \$-2\$.

Use \$L^AT_EX\$, It makes our work a lot easier!