4-2^2+5x3-2=11

[JustALooseScrew]

Wiccan of Darkness said:

I think this is a trick question.

First, put the brackets around the 4-2 to give (4-2)^2 + 5 x 3 -2.

Now expand the brackets... (4-2)^2

(4-2) x(4-2)

Now remove the brackets....

4 - 2 x 4 - 2

Now add brackets again....

(4-2) x 4 - 2

2x4 =8
-2 =6
now add 5 x (3-2)
which is 5 x 1

6 plus the 5 is 11.

As far as I can see, that's the only way forward. I can't see how it's cheating, as you've added the brackets around the (4-2)^2 and simply expanded the brackets, then done as the question asked and re-added the brackets as per the question.

Burn the witch!!!!!


(any chance of this week's lottery numbers?)

[V8LM]

Expanding the square is just cheating. You might as well say

= 11

= 1+1+1+1+1+1+1+1+1+1+1

= (1+1+1+1+1+1)(+1+1)(+1)(+1)+1

= 13

[JuanCarlosFandango]

That's rubbish.

[Wiccan of Darkness]

chemistry said:

So....he won the buttons!!!!

Also, here’s the official (trick) answer from the teacher:



Thanks again for everyone’s help!

Hahahahahaha!!

What did I put on page 1........?

(do I get a button?)

Edited by Wiccan of Darkness on Tuesday 16th October 21:27

[FarmyardPants]

Those that can, do.
Those that can't, teach.
Those that can't teach, cheat!

[Mr Pointy]

That's just completely unacceptable.

Can you get him to explain exactly what the pupils were meant to learn from this?

[FarmyardPants]

JustALooseScrew said:

Wiccan of Darkness said:

I think this is a trick question.

First, put the brackets around the 4-2 to give (4-2)^2 + 5 x 3 -2.

Now expand the brackets... (4-2)^2

(4-2) x(4-2)

Now remove the brackets....

4 - 2 x 4 - 2

Now add brackets again....

(4-2) x 4 - 2

2x4 =8
-2 =6
now add 5 x (3-2)
which is 5 x 1

6 plus the 5 is 11.

As far as I can see, that's the only way forward. I can't see how it's cheating, as you've added the brackets around the (4-2)^2 and simply expanded the brackets, then done as the question asked and re-added the brackets as per the question.

Burn the witch!!!!!


(any chance of this week's lottery numbers?)

Probably the teacher reads PH and this is the best get-out he could find

[Cyder]

Oh come on!

I've got an A level in Maffs and a degree in Aerospace Enjuneering and I couldn't work that out.

Bloody teachers thinking they're so smart.

[skahigh]

Original question said:

Add the necessary brackets to make this equation true

This says nothing about solving the equation and adding/removing brackets as you go.

Surely once you add brackets, partially solve and add more brackets you are adding brackets to a different equation?

Utter tripe from the teacher.

[schmunk]

FarmyardPants said:

Those that can, do.
Those that can't, teach.
Those that can't teach, cheat!

Those who can, teach.

Those who can't, teach PE.

[Toltec]

With enough iterations you could get any number you wanted doing that.

Here is one for you to work out

e^iπ + 1 = 0

e^iπ = -1

iπ = ln(-1)

iπ = 1/2.ln(-1^2)

1 = 1/(2iπ).ln(1)

However as ln(1) = 0

1 = 1/(2iπ).0

1 = 0

[JustALooseScrew]

^ Is that Euler's group theory?

I'm not a mathematician, at school in the 1980s I found most of the AS-Level maths utterly irrelevant to what I wanted to do in life - i.e. chop up bits of metal and weld them back together into something more useful.

In the last few months I've discovered a fond interest in mathematics, mainly because my son has just started secondary school and I feel I need to be at least one step ahead of what they are teaching him, and also be in a position to really explain, not just what, but why.

Over the last few years myself and my father have been priming him (see what I did there?) into fully understanding Pythagoras theorem.

He's been introduced into what a sin, cos and tan actually mean in terms of a measure of the ratio of two numbers, and what these ratios actually represent.

Last week I gave him a blinder to use in class with the expansion of (a+b)^2 being equal to a^2 + 2ab + b^2.

Now he can figure out in his head the square of any number up to 100 faster than most kids can reach into their bags to pull out a calculator.

I'm always looking to be one step ahead, see my post on the Riemann Hypnosis which I find utterly fascinating, it's due a revisit once I've done some more learning.

A lot of this (proper maths) stuff is way out of my league in terms of being able to actually do it, but I love being able to follow it.

I suppose it's a bit like being asked to design an automatic gearbox - I haven't got a clue, but I know what it does.

ETA:
Here's a couple of what I think are interesting youtube sites on this stuff:
3Blue1Brown
Mathologer

[gothatway]

Sign up to https://brilliant.org/courses/#recent (no connection other than as an occasional user) for free maths stuff and puzzles at all levels.

[Toltec]

Euler's Identity or Equation, I derived it myself when studying complex numbers at school in the early 80's, one of my favourites.

The thing above stumped my teacher for a bit, looks reasonable at first however there is a big flaw which makes it impossible.

[Simpo Two]

He's done it the same way Rachel Riley does it on Countdown.

Maybe that's where he got the idea from?

And is it in the syllabus?

[V8LM]

Toltec said:

i.pi = ln(-1)

ln(-1) is undefined for real numbers, but as we are using complex numbers then

ln(-1) = ln(1) + i.pi

so i.pi = i.pi

[ben5575]

See, I’m alright with maths, right until you go and start doing silly things like that.

How can a number not be a number and be a complex number or even an imaginary one ffs?! It’s just silly.

[wilwak]

chemistry said:

So....he won the buttons!!!!

Also, here’s the official (trick) answer from the teacher:



Thanks again for everyone’s help!

Oh gosh. What a bodge answer!

[annodomini2]

wilwak said:

chemistry said:

So....he won the buttons!!!!

Also, here’s the official (trick) answer from the teacher:



Thanks again for everyone’s help!

Oh gosh. What a bodge answer!

I would argue this is in breach of the original statement as it states "add necessary brackets" not rearrange the equation.