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Title: 14 year old's maths homework problem Post by: redimp on November 11, 2008, 09:59:18 PM Solving Double Inequalities
Ok guys, we have come so far with these but now we're a little bit stuck. Here's the one we can solve and how we do it :- 13<2x+5<15 - by subtracting 5 we now have 8<2x<10 - by dividing the x value into the two outer numbers we get 4<x<5 which is the answer. So how would we go about solving this one x+13<3x+5<3x+11. The answer is 4<x<3 (apparently) Thanks in advance Pete and Shell Title: Re: 14 year old's maths homework problem Post by: Graham C on November 11, 2008, 10:05:13 PM 14 year old? You sure it's not masters level applied maths?
Title: Re: 14 year old's maths homework problem Post by: kinboshi on November 11, 2008, 10:08:26 PM How can x be greater than 4, but less than 3?
Title: Re: 14 year old's maths homework problem Post by: action man on November 11, 2008, 10:08:52 PM xis 4.5
Title: Re: 14 year old's maths homework problem Post by: bolt pp on November 11, 2008, 10:09:41 PM they wonder why kids skip school?
girls are cleverer than boys though, boys just want to play football and stuff(i was getting up to a lot of stuff at 14 that would put the modern day so called"hoodies"to shame) whereas girls seem more focused. Title: Re: 14 year old's maths homework problem Post by: bolt pp on November 11, 2008, 10:10:52 PM How can x be greater than 4, but less than 3? magic x innit Title: Re: 14 year old's maths homework problem Post by: Jon MW on November 11, 2008, 10:27:51 PM x+13 < 3x + 5 < 3x + 11
subtract x+5 8 < 2x < 2x + 6 divide by 2 4 < x < x + 3 My apologies if I've missed anything but this makes more sense than 4<x<3 Title: Re: 14 year old's maths homework problem Post by: Longy on November 11, 2008, 10:34:41 PM x+13 < 3x + 5 < 3x + 11 subtract x+5 8 < 2x < 2x + 6 divide by 2 4 < x < x + 3 My apologies if I've missed anything but this makes more sense than 4<x<3 Yup this looks right. Misprint in the answers no doubt. Title: Re: 14 year old's maths homework problem Post by: Rupert on November 11, 2008, 11:31:12 PM Quote The answer is 4<x<3 (apparently) lol Title: Re: 14 year old's maths homework problem Post by: snoopy1239 on November 12, 2008, 02:16:37 AM x+13 < 3x + 5 < 3x + 11 subtract x+5 8 < 2x < 2x + 6 divide by 2 4 < x < x + 3 My apologies if I've missed anything but this makes more sense than 4<x<3 Looks good. Original answer is clearly gibberish. I'd imagine they want it with as few 'x' as possible though. Title: Re: 14 year old's maths homework problem Post by: kinboshi on November 12, 2008, 09:48:13 AM x < x + 3 is particularly useful to know.
I think they probably have the correct answer, but they have made a mistake with the original statement. The same as the question to life, the universe and everything. Title: Re: 14 year old's maths homework problem Post by: Sark79 on November 12, 2008, 07:24:16 PM I feel ill after reading this thread. I really hate maths, it is so difficult and confusing. Words are much more fun than numbers. I was given Bill Chen's book about poker maths as a gift earlier this year and I flicked through it before donating it to pdsa in Kilmarnock a day later. I am ok with basic poker maths, but the maths in this thread hurts my head.
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