• ### Please explain how to do this.?

Calculate the values of x for which A is invertible A= 2 -2 -2 -1 x 4 3 -3 x I just haven't a clue - and I'm trying to help my daughter with it. :-(
Calculate the values of x for which A is invertible A= 2 -2 -2 -1 x 4 3 -3 x I just haven't a clue - and I'm trying to help my daughter with it. :-(
1 answer · Mathematics · 9 years ago
• ### Can I use printer ink for my fountain pen?

I was wondering if there is any reason why I couldn't use inkjet refill ink for my fountain pen. Would it clog up too much? has anyone else tried it?
I was wondering if there is any reason why I couldn't use inkjet refill ink for my fountain pen. Would it clog up too much? has anyone else tried it?
9 answers · Drawing & Illustration · 10 years ago
• ### How old is my mum?

I am 42 - I have an older brother and also a younger one. Closest to her actual age gets 10 points!
I am 42 - I have an older brother and also a younger one. Closest to her actual age gets 10 points!
• ### Who likes chess?

my wife thinks I'm strange because I like to play chess. Am I? Maybe chess is old fashioned now - young people want electronic stuff and a traditional game like chess seems boring but I love it. Any thoughts?
my wife thinks I'm strange because I like to play chess. Am I? Maybe chess is old fashioned now - young people want electronic stuff and a traditional game like chess seems boring but I love it. Any thoughts?
• ### Most venomous creature?

I have had a long lasting debate with a friend about this. He says it's the box jellyfish but I say it's one of the sea snakes (cant remember which one) I seem to remember watching some tv prog (david attenborough) and he said that the snake WAS the most venomous but very rarely bites and it could be handled safely. But I need evidence... show more
I have had a long lasting debate with a friend about this. He says it's the box jellyfish but I say it's one of the sea snakes (cant remember which one) I seem to remember watching some tv prog (david attenborough) and he said that the snake WAS the most venomous but very rarely bites and it could be handled safely. But I need evidence to show my friend, or to convince myself that I'm wrong I am not interested in daddy longlegs - harmless. Or poison arrow tree frogs - no venom, only very toxic slime If you can find a source it would be great. Oh bye the way is there a way to scientifically determine the potency of a venom - since they act in different ways?
• ### Has anyone been to John O'groats?

If you have could you tell me what you thought of the place, and what is like. Is there a pub? and shops etc. A few of us are thinking of going camping there in a couple of weeks. I've heard there are some fantastic cliffs.
If you have could you tell me what you thought of the place, and what is like. Is there a pub? and shops etc. A few of us are thinking of going camping there in a couple of weeks. I've heard there are some fantastic cliffs.