Maths help please

Yozz76 · 1 Dec 2010 at 18:21

I'm helping my daughter with her maths homework but I'm afraid that maths is not a strong point for either of us. We have answered the following questions but we are uncertain that we are applying the correct rules (I did suggest I wasn't good at maths!). It is not the answers that I'm after (We have included what we think they are), just looking for reassurrance that we have applied the correct rules?

2a - 2 when a = 4 = 6

10(c - 5) when c = 9 = 40

n - 38 / 5 when n = 3 = -7

9p - 18 / 6 when p = 8 = 9

6t + 7 when t = -6 = -29

nydryl · 1 Dec 2010 at 18:23

The second last is wrong. You should do 18/6=3 and take that away from 9*8=72 so the answer is 69.

Apart from that it looks all good.

Haircut · 1 Dec 2010 at 18:25

Well, 3 and 4 are wrong if you're applying order of operations correctly.
Others look correct though

Ciphon · 1 Dec 2010 at 18:26

Well if you know that a = 4 then the top one would be 2 * 4 - 2, which would be correct.

2nd one is 10 * (9 - 5), which is 40.. again correct.

3rd: 3 - 38 / 5.. again correct...

Won't bother checking the others - looks to me like you've done them correctly.

Edit: lol.. beaten - also looks like I should have looked at the last two

SiriusB · 1 Dec 2010 at 18:27

EDIT: You should put brackets around parts that go together.

9p - 18/6 can be

9p - (18/6)

or

9p - 18
--------
6

Hence people's confusion..

Amleto · 1 Dec 2010 at 18:28

Ciphon said:
Well if you know that a = 4 then the top one would be 2 * 4 - 2, which would be correct.

2nd one is 10 * (9 - 5), which is 40.. again correct.

3rd: 3 - 38 / 5.. again correct...

Won't bother checking the others - looks to me like you've done them correctly.

Edit: lol.. beaten - also looks like I should have looked at the last two

3rd is wrong

nydryl · 1 Dec 2010 at 18:31

I just assumed you missed out brackets in the 3rd one as teachers normally make the answer an integer.

crunchman · 1 Dec 2010 at 18:32

nydryl said:
I just assumed you missed out brackets in the 3rd one as teachers normally make the answer an integer.

Yea it doesnt look like the sort of value you'd expect to be working with at that level

Haydz · 1 Dec 2010 at 18:35

Well, according to BODMASS, a division comes before addition/subtraction, therefore both 3. and 4. would be incorrect, unless of course it's supposed to be bracketed.

Quite strange that those answers aren't all whole integers though.

Edit: Beaten >.>

Deadbeat · 1 Dec 2010 at 18:43

Nobody noticed that the first one is wrong yet?

Edit: facepalm - ignore

Yozz76 · 1 Dec 2010 at 19:06

SiriusB said:
EDIT: You should put brackets around parts that go together.

9p - 18/6 can be

9p - (18/6)

or

9p - 18
--------
6

Hence people's confusion..

Thx Sirius,

9p - 18
--------
6

Is how I should have presented it. We now have the reassurance we need so thanks guys. (Damn it has been too long since my miserable math efforts at school!)