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# P2 maths- help pls watch

1. how do u work out what the value of 'w' is?

e^-w = 4

thanx
2. (Original post by wonkey)
how do u work out what the value of 'w' is?

e^-w = 4

thanx
hi,
take ln on both sides
u will get:
-w=ln 4
so, -w=2*ln 2
so, -w=2*0.693
so, w=-1.386
3. (Original post by prince_capri)
hi,
take ln on both sides
u will get:
-w=ln 4
so, -w=2*ln 2
so, -w=2*0.693
so, w=-1.386
hey, thanks for that.........is the * meant to be multiply?
so say its ln8.....can i turn that into 2ln4?
4. ln 8 does not equal 2ln 4.

ln 8 = ln (2^3)

There's a log law that says ln (a^n) = nln a

Therefore, ln 8 = 3ln 2.
5. (Original post by Nylex)
ln 8 does not equal 2ln 4.

ln 8 = ln (2^3)

There's a log law that says ln (a^n) = nln a

Therefore, ln 8 = 3ln 2.

ah i get it, thank u!
6. (Original post by wonkey)
hey, thanks for that.........is the * meant to be multiply?
so say its ln8.....can i turn that into 2ln4?
* is meant for multiply
But ln 8 is not equal to 2*ln 4
the reason is that ln 8=ln 2^3, and so its equal to 3*ln 2

if u r unable to understand this part, i suggest that u have a quick read thru ln rules..and u will find the answer.
All the best
7. how do you go about working out 'z':

cosz + sinz = 1/3

thank u
8. if u square both sides, u will get:

cos^2 z + 2sin z cos z + sin^2 z = 1/9

and u can use the identities to get:

1 + sin 2z = 1/9

thus sin 2z = -8/9 and so on.
9. (Original post by 4Ed)
if u square both sides, u will get:

cos^2 z + 2sin z cos z + sin^2 z = 1/9

and u can use the identities to get:

1 + sin 2z = 1/9

thus sin 2z = -8/9 and so on.

thanks
10. Good evening Gentlemen, I believe your question is concerning the involvement of ‘R’ and ‘∂ (alpha)’.

Furthermore by using the above method the answers I obtained were -31.4, 121.4, 328.6........

11. 2*ln2 is not the same as 2ln2
12. (Original post by Bhaal85)
2*ln2 is not the same as 2ln2
Doesn't that give ln4?
13. (Original post by Bhaal85)
2*ln2 is not the same as 2ln2
What? Of course it is, the multiplication operator is implied in 2ln2.

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