Maths help!

(23 Posts)
MrsFogi Sun 06-Nov-16 15:58:10

I know the answer is simple but I can't find a simple explanation on the net (no doubt I am searching for the wrong thing). So the question is "Find two consecutive numbers with the product of 182. This is how far I've got: x(x+1)=182 I take it I then take 1 from 182 so x(x) = 181 what do I do now (on calculator)? At this rate I'm going to be stripped of my maths GCSE sad, dd is only in year 4 and I'm stumped already!

StealthPolarBear Sun 06-Nov-16 16:01:46

No you need to multiply both parts of the bracket by x
so x (x+1) becomes x^2 + x =182

StealthPolarBear Sun 06-Nov-16 16:03:38

x^2 + x - 182 = 0

And then there is a the quadratic equation you can use

If they want methodology. Otherwise find the square root Iof 182 ans it'll have to be the number below and number above surely

StealthPolarBear Sun 06-Nov-16 16:04:36

Sqrt is 13.something

ThatGingerOne Sun 06-Nov-16 16:05:14

13 and 14

Pestilence13610 Sun 06-Nov-16 16:05:36

You didn't multiply your brackets so that way wont work. Also not the way they would do it in year 4.
Try experimentation
12 x 12 = 144
too small
13 x 13 = 169
still too small
14 x 14 = 196
too big
Have you got an idea what hose consecutive numbers are yet?
13 x 14 should be your next move

SunnySomer Sun 06-Nov-16 16:07:07

You have got me really worried that my Y5 is a complete simpleton as he never gets asked this stuff for homework.....

SunnySomer Sun 06-Nov-16 16:08:01

(But if he had I would have advocated Pestilence's method!)

Bin85 Sun 06-Nov-16 16:08:10

Trial and error
Not 11x12 =132
Not 12x 13 =156
But 13x14 =182

StealthPolarBear Sun 06-Nov-16 16:08:49

The non equation way would be to find the square root surely!

WeAllHaveWings Sun 06-Nov-16 16:23:10

surely in Y4 they wouldn't be going anywhere near equations and you are over thinking this? Its all about estimating and trial and error at this stage (or it was for ds).

Does your dd say they use equations in class?

RafaIsTheKingOfClay Sun 06-Nov-16 16:44:52

For yr4 I'd go with trial and error, possibly using known number facts to work out where to start.

12*12=144 which is smaller than 182, but not by much, so the answer has to be two consecutive numbers around there but with the smallest being at least 12.

irvineoneohone Sun 06-Nov-16 17:39:12

I just asked my ds(yr4).
He answered in few seconds. Asked how he did it, he said exactly same as
Bin85 's answer.

ShoeEatingMonster Sun 06-Nov-16 18:29:13

You are completely over thinking this! Algebra doesn't come into the NC until Y6!
You need to be doing a trial and improvement approach as mentioned above.

MrsFogi Sun 06-Nov-16 21:41:01

Thanks all for calming me in my panic - I have stepped away from the algebra and shown dd the square root button!

irvineoneohone Sun 06-Nov-16 22:12:24

I don't think you need square root for this?

Other easy way of doing this is prime factorize 182 to 2*7*13, and it's esay to see it's 13x14, I think.

StealthPolarBear Sun 06-Nov-16 22:27:25

Why isn't square root as valid as any other method?

RafaIsTheKingOfClay Sun 06-Nov-16 22:40:07

It is valid, it's just that yr 4 children won't normally have been taught that yet so they wouldn't be expected to use it to solve this.

I'm not sure the concept of square numbers appears until year 5.

ShoeEatingMonster Sun 06-Nov-16 23:00:52

^^
Square numbers aren't taught until year 5

irvineoneohone Mon 07-Nov-16 06:22:39

StealthPolarBear, my ds is very familiar with square numbers and square roots. But I don't expect him to just use calculator in yr4, when faced with this type of question!!!

In fact, even using algebra, you still need to factorize 182, so trial and error would be most appropriate method for yr4, imo.

x(x+1) = 182 x^2 + x-182 = 0 (x-13)(x+14)=0
x= 13, -14
So in this case x= 13 13+1=14 Answer 13x14=182
No way yr4 should be doing this.

StealthPolarBear Mon 07-Nov-16 06:29:37

Glad to hear it my year 5 certainly couldn't!

amihuman Mon 07-Nov-16 06:35:39

Um this is your dc homework? How does he/she want to solve it? This presumably links to work they've done in class? So either let him have a go with the strategy he was taught in class or, if he really has no idea, explain to the teacher that he couldn't do it. If he can't do the work then teacher needs to know that.

irvineoneohone Mon 07-Nov-16 08:08:32

There was sort of similar question I did recently with my ds. It was rather good one, although the number is bigger and not consecutive and can have multiple answers.
My ds used trial and error, I cheated and used prime factorization.

mathszone.co.uk/blog/the-2016-question/

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