Maths help please!

ivrytwr3 · 27 Mar 2010 at 13:53

The line with equation y=2x-k passes through the point (4 , 0). Work out the value of k.

Where do i start and what's the simplest way of remembering how to do these?

tntcoder · 27 Mar 2010 at 13:56

This is probably wrong (im tired), but isn't it just x=4 y=0
0 = 2*4 - k
0 = 8 - k
k = 8

ivrytwr3 · 27 Mar 2010 at 13:59

and more:

Simplify:

(1)0 (in brackets, 1 over p, outside brackets, to power of zero)

-

p

(r4)-2 (in brackets, r to the power of 4, outside brackets, to power of minus 2)

danza · 27 Mar 2010 at 14:00

k = 8

ivrytwr3 · 27 Mar 2010 at 14:01

the answer is 8 (to first question) - how did you do the working?

tntcoder · 27 Mar 2010 at 14:02

ivrytwr3 said:
the answer is 8 (to first question) - how did you do the working?

Basic primary school algebra, workings in my post...

ivrytwr3 · 27 Mar 2010 at 14:04

lol, not 'clicking' with me. I don't see how you do it

Sinopa · 27 Mar 2010 at 14:05

The point (4 ,0) is an x,y co-ordinate, x being 4 and y being 0.

Put these two numbers into your equation and you get 0=8-k. So, 8 minus something (k) equals 0. That means k must be 8. Simples!

(Just in case you don't know, the 2x in your equation means 2 times x which is how I got 8)

wannabedamned · 27 Mar 2010 at 14:08

Algebra is one of the few things I was good at, Although the (4, 0) Threw me, But now I think about it, Its obviously co-ordinates.

I suck at maths on a grand scale, I'm sure if i was to take a maths GCSE i'd probably get a D or something

ivrytwr3 · 27 Mar 2010 at 14:11

sinopa, spot on! Got it, thanks!

Destination · 27 Mar 2010 at 14:21

What level of maths are you studying for?

Serious question, not trolling.

ivrytwr3 · 27 Mar 2010 at 14:21

GCSE core (grade c - g)

Throrik · 27 Mar 2010 at 14:28

Destination · 27 Mar 2010 at 14:41

ivrytwr3 said:
GCSE core (grade c - g)

ok thx for info

aaron333 · 27 Mar 2010 at 14:45

ivrytwr3 said:
The line with equation y=2x-k passes through the point (4 , 0). Work out the value of k.

Where do i start and what's the simplest way of remembering how to do these?

Substitute what you know

(4, 0 )

4 = X value
0 = Y Value

0 = (2 x 4) - k
0= 8-k
K = 8

EDIT: Should read before posting!

ivrytwr3 · 27 Mar 2010 at 14:51

is that easier to understand?

frying_pan_cat · 27 Mar 2010 at 15:19

The answer to the (1/p)^0 one is 1 since anything to the power 0 is 1.

As for (r^4)^{-2} you just add the powers, so the answer is r^2 (where ^ denotes powers)

Edit: as Jay Psi pointed out I'm an idiot and got the second part wrong :rolleyes:

. See further down for correct answer

ivrytwr3 · 27 Mar 2010 at 16:10

thank you! Also, can you do those on your calc?

Jay Psi · 27 Mar 2010 at 17:20

frying_pan_cat said:
As for (r^4)^{-2} you just add the powers, so the answer is r^2 (where ^ denotes powers)

Okay, it's been a few years, but are you sure about this? IIRC, raised indices are multiplicative, so (r^4)^(-2) = r^(4*-2) = r^(-8) = 1/(r^8).

If it was (r^4)*(r^-2) then the answer would be r^2 [as the OP had in 16 (b), where (q^5)*(q^3) = q^(5+3) = q^8]. Unless I've dropped a *BIG* one there

EDIT - These algebraic simplifications can be done on certain calculators, but I'm confident they're not allowed for your exams

meghatronic · 27 Mar 2010 at 17:26

Sigh.

http://www.wolframalpha.com/input/?i=y=2x-k+where+x=4,+y=0