Year 12s: what will be the first way you research your future options? >>

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C4 help!

How do you solve tan2x = 4tanx? And how I've reached 2tanx/(1-tan^2x)

Original post by casablancas123

How do you solve tan2x = 4tanx? And how I've reached 2tanx/(1-tan^2x)

2\tan x = 4 \tan x (1-\tan^2 x)

Can you continue from there?

OP

Original post by BabyMaths

2\tan x = 4 \tan x (1-\tan^2 x)

Can you continue from there?

So that we give me 2tanx= 4tanx -4tan^3x? :s

OP

Original post by BabyMaths

2\tan x = 4 \tan x (1-\tan^2 x)

Can you continue from there?

Or do I then divide by 4tanx to get 1/2 = 1-tan^2x?

Original post by casablancas123

So that we give me 2tanx= 4tanx -4tan^3x? :s

Subtract

2\tan x

from both sides and then factorise.

OP

Original post by BabyMaths

Subtract

2\tan x

from both sides and then factorise.

And what would that give? Sorry I'm just really confused haha

Original post by casablancas123

And what would that give? Sorry I'm just really confused haha

Are you asking what we get when we subtract

2 \tan x

from both sides?

OP

Original post by BabyMaths

Are you asking what we get when we subtract

2 \tan x

from both sides?

Yes

Original post by casablancas123

Yes

2tanx= 4tanx -4tan^3x

2tanx-2tanx= 4tanx -4tan^3x-2tanx

0= 4tanx -4tan^3x-2tanx

You do the rest, although you really should be able to subtract 2tanx from each side without problem by now.

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