Maths question help please!
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Maths question help please!
Hi all. Unfortunately the last time I did any algebra was many, many years ago and I don't remember being any good at it then! I wonder if I could get some help?
In the following question does it matter which side you start on?
36k+15 = 50k-27
I'm sure this is pretty basic stuff to most of you but I can't get my head around it!
Do I need to cancel out the - number first?
Confused!
In the following question does it matter which side you start on?
36k+15 = 50k-27
I'm sure this is pretty basic stuff to most of you but I can't get my head around it!
Do I need to cancel out the - number first?
Confused!
Re: Maths question help please!
I'm sure a maths teacher will be on to tell you how to do it soon but this is how I would do it:
36k + 15 = 50K - 27
Add 27 to both sides
36k + 15 + 27 = 50k
36k + 42 = 50k
Minus 36k from both sides
42 = 50k - 36k
42 = 14k
3 = k
Does that help?
36k + 15 = 50K - 27
Add 27 to both sides
36k + 15 + 27 = 50k
36k + 42 = 50k
Minus 36k from both sides
42 = 50k - 36k
42 = 14k
3 = k
Does that help?
Re: Maths question help please!
Great thanks!
Yes it does help as that was how I was thinking I would do it.
Would it change do you know if the minus number was on the other side? So ..
19u-36 = 45u+16
Would I then start by adding 36?
Yes it does help as that was how I was thinking I would do it.
Would it change do you know if the minus number was on the other side? So ..
19u-36 = 45u+16
Would I then start by adding 36?
Re: Maths question help please!
As a maths teacher I would always look at the unknown term first and decide which side of the equation had most. In this case the RHS has more u so I will need to collect u on that side and constants on the other.thescribe wrote:Great thanks!
Yes it does help as that was how I was thinking I would do it.
Would it change do you know if the minus number was on the other side? So ..
19u-36 = 45u+16
Would I then start by adding 36?
-16 from both sides (the balance method)
19u - 36 - 16 = 45u
so -19u from both sides
etc.
What year group is this for?
What are you doing when you solve an equation? [More important than the 'method' is understanding the meaning of the answer]
Re: Maths question help please!
Thank you!
He's in Y5 but this is something his tutor has given him for grammar prep. We thought he had understood it but he says he got it wrong and unfortunately my son got quite upset during the session and completely forgot what he told him about what had been done wrong etc.
This is how he did it:
19u + 36 = 45u -16
-36 on both sides
19u = 45u-52
-45u on both sides
-26u/-26 = -52/-26
u = 2
Its all over my head I'm afraid
He's in Y5 but this is something his tutor has given him for grammar prep. We thought he had understood it but he says he got it wrong and unfortunately my son got quite upset during the session and completely forgot what he told him about what had been done wrong etc.
This is how he did it:
19u + 36 = 45u -16
-36 on both sides
19u = 45u-52
-45u on both sides
-26u/-26 = -52/-26
u = 2
Its all over my head I'm afraid
Re: Maths question help please!
My dd is in year 7 and did this earlier this term. She didn't do it at all for her grammar preparation. maybe you need it where you are but it might be worth finding out?
Re: Maths question help please!
Yes it looks too hard for GS prep ... which is why I asked.
What you are doing when you solve a linear equation in one unknown is fidning the ONE value of the unknown that makes the equation true.
What you are doing when you solve a linear equation in one unknown is fidning the ONE value of the unknown that makes the equation true.
Re: Maths question help please!
Having now "officially" retired from posting on this site, my DC having accepted their offered 2015 GS place, I'm just calling in briefly to show the straightforward way I was taught (many more moons ago than you might imagine) to do this kind of problem.
36k + 15 = 50k -27
rewrite as: + 36k +15 = + 50k - 27
move the + 36k and the - 27 across when they then become -36k and + 27 respectively and thus rewrite as: + 15 + 27 = + 50k - 36k
which is: 42 = 14k (i.e. 14 x k)
and therefore: 42/14 = k
hence: k = 3
Simples, as they say these days!
36k + 15 = 50k -27
rewrite as: + 36k +15 = + 50k - 27
move the + 36k and the - 27 across when they then become -36k and + 27 respectively and thus rewrite as: + 15 + 27 = + 50k - 36k
which is: 42 = 14k (i.e. 14 x k)
and therefore: 42/14 = k
hence: k = 3
Simples, as they say these days!
Re: Maths question help please!
thanks for all the replies.
I must admit I think it's hard, especially as they've not even done algebra at school yet and he's one of the youngest in the class too. (not sure that matters!)
But, his tutor only tutors for Grammar prep and has done for years and he says it's necessary so now I'm wondering if he's pushing too hard!
I must admit I think it's hard, especially as they've not even done algebra at school yet and he's one of the youngest in the class too. (not sure that matters!)
But, his tutor only tutors for Grammar prep and has done for years and he says it's necessary so now I'm wondering if he's pushing too hard!
Re: Maths question help please!
Please ignore equilibrio's method - swapping sides and swapping signs does NOT make sense!
When he suggests this step
The balance (or inverse operation) method is clear and needs no tricks.
When he suggests this step
note the 14 is 'swapping sides' but does not change sign - this is why this method is NOT taught now.which is: 42 = 14k (i.e. 14 x k)
and therefore: 42/14 = k
The balance (or inverse operation) method is clear and needs no tricks.
Last edited by Guest55 on Wed Mar 04, 2015 11:42 pm, edited 1 time in total.