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# Maths Issues?

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1. Anyone know how to solve this?
c=7n + 2(n - 1)
1.) express c in terms of n (multiply brackets)
2.)express n in terms of c

Also
Given that tan x = 3
write down the value of a) sin x b) cos x
2. 1.

We know that

So

2.

So

3. Draw a right-angled triangle. We know tanx=opposite/adjacent. So label an angle x (obviously not the right angle). Label the opposite side 3 and the adjacent 1 (since this gives tanx=3). Then use pythagoras to find the hypotenuse i.e . Now use the fact that sinx=opposite/hypotenuse and cosx=adjacent/hypotenuse.
3. (Original post by Math12345)
1.

We know that

So

2.

So

3. Draw a right-angled triangle. We know tanx=opposite/adjacent. So label an angle x (obviously not the right angle). Label the opposite side 3 and the adjacent 1 (since this gives tanx=3). Then use Pythagoras to find the hypotenuse i.e . Now use the fact that sinx=opposite/hypotenuse and cosx=adjacent/hypotenuse.
Thank you so much!
This helped a lot, any chance you could help with this one?
9x + x^2 = 0 (Solve)
Would it just be x=0, x=9
or do I have to rearrange to find x?
4. (Original post by CresentHan)
Thank you so much!
This helped a lot, any chance you could help with this one?
9x + x^2 = 0 (Solve)
Would it just be x=0, x=9
or do I have to rearrange to find x?
9x+x^2=0
Factorise: x(9+x)=0
x=0, x=-9 (not 9)

You can check your solutions by subbing them back in:
9(0)+(0)^2=0+0=0 so 0 is a solution like we claimed
9(-9)+(-9)^2=-81+81=0 so -9 is a solution like we claimed

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