Question

On 6.189 Handout 1Exercise 1.4 can someone explain the equations to me please?

Maths was never my strong point especially when it came to understanding equations.

Answer 1

What part is giving you trouble?

Answer 2

Just the symbols really.

Answer 3

There are a few there, could you be specific? :D

Answer 4

Number 2 above the 7 + 9 I would assume its divide. But on number 4 the same symbol is there but with a small number 4.

Answer 5

Do you mean part II where it has \(\frac{3*5}{2+3}\)?

Answer 6

OH, you mean the root \(\sqrt{}\)

Answer 7

Yeah. What on earth do the symbol mean?

Answer 8

The first one, \(\sqrt{7+9}\) is a square root symbol, it represents the number (when multiplied by itself) equals 16, which is 7+9.

Answer 9

The second one, \(\sqrt[4]{-19+100}\) is a 4th root and it represents the number (when multiplied by itself 4 times) equals 81, which is -19+100.

Answer 10

In the first example, can you determine the number, when multiplied by itself (or squared) gives you 16?

Answer 11

Is the first one not asking for the square root of 16 x 2?

Answer 12

Which is 8.

Answer 13

Exactly.

Answer 14

And the 4th root of 81?

Answer 15

324

Answer 16

For the 4th root, you are wanting a number that multiplies itself 4 times to equal 81. For example, the 4th root of 16 is 2, because 2*2*2*2=16

Answer 17

20.25 which is a float.

Answer 18

Nope Hang on

Answer 19

3.

But that was trial and error to figure out.

Answer 20

Nice work.

Answer 21

An easier way would be to realize that 81 has a square root of 9, since 9*9=81
Also, the square root of 9 is 3, since 3*3=9. Place into your previous example and you have 3*3*3*3=81

Answer 22

However this is a programming class, so you don't care so much about the math. :)

Answer 23

And number 3 is just the result of 4-7 * 3 effectively?

Answer 24

Question 3 i mean.

Answer 25

That is the result of 4-7, cubed.

Answer 26

So you subtract 7 from 4, then you take the result and multiply it by itself 3 times.

Answer 27

Hah I was originally going to say that. But that is what I meant.

I'm not good at maths when it's explained in the way it was set out as maths equations and formula were never my strong point, heck my maths is below average I'd say.

But having it explained by you means i have a rough idea now on how to code it and get a correct result.

Answer 28

That's good, I would hate to be confusing things further. :P

Answer 29

A shame I can only give you one "Best Response" medal. Cheers very much.

Answer 30

It all works out, eventually you'll ask another question on a new thread and I can try and gain another medal. :D

Answer 31

eSpeX - how to you write 4thRoot in python without too much hassle? I tried 4*sqrt(-11+100) and that was off.

Answer 32

I think you sqrt the number and then sqrt the result?

Answer 33

The equation you wrote is multiplying 4 by the square root of -11+100.
I chose to write it as a fractional exponent: print ((-19+100)**(1/4.0))

Answer 34

I need more math lessons. Ha. But that seems to make sense. The sqrt of x is x ** 1/2.0 or .5 and that makes 1/4.00 the quad root? Ha...

Answer 35

Yes, exactly.

Answer 36

+1, like, upvote, whatever this place does... Thanks for helping.

Answer 37

It's the "Best Response" buttons on the replies, and you are welcome.

Answer 38

Coming back to this equation



7 + 9 = 16
16 x 2 = 32
Sqrt of 32 = 5.65

Is that right or have I muddled myself up again?

Answer 39

\[\sqrt{7+9} \times2\]

Answer 40

you want to do the sqrt first then multiple x 2

Answer 41

Order of operations looks at a sqrt the same as parenthesis, I believe. They come first. so the step is this: 7+9 = 16 the sqrt of 16 is 4. 4 * 2 is 8.

At least that's my understanding.

Answer 42

sqrt(7+9) * 2

Answer 43

Exactly.

Answer 44

Yeah made sense as soon as you said it. Problem is I had it last night thanks to eSpeX but having been to sleep and work, coming back to code it, the damn thing just wasn't fresh in my mind anymore.

Answer 45

If you think about the order of operations, PEMDAS, the root is an exponent, and so it would be carried out before the multiplication.

Answer 46

Once we have completed the code in the assignments how would we go about comparing it with each others code?

Answer 47

You can always post it onto one of the paste sites.

Answer 48

- http://dpaste.com
- http://pastebin.com
- http://www.repl.it/
- http://pastie.org
- http://codepad.org
- http://ideone.com