Maths Help

[pickylock26]

Can anybody explain to me how to solve any of theses

 

 

 

[Aytex]

wat is this. linusmathtips>?

[Castdeath97]

Most of us are brain dead now after summer, if you asked this to me 4 months ago I would have answered it.

[Nineshadow]

They are pretty easy though.

 

sin²x =1 + cosx

We know that :

sin²x = 1 - cos²x

We replace and end up with :

1-cos²x = 1 + cosx

-cos²x=cosx

cosx+cos²x=0

cosx(1+cosx)=0

This has two solutions :

1. cosx=0
2. 1+cosx = 0 => cosx=-1

Knowing that 0<=x<2*pi , then the answers are :

1. for cosx = 0 the solution is pi/2
2. cosx = -1 => x must be 2*pi, but x < 2*pi so there is no solution here.

Final answer : x = pi/2 = 90 deg

[arronleeds]

brah you have just fried my brain, I remember doing decent at maths in school (high C grade) but now i dont remember shit

 

before anyone says "a C is ok" i could have done better but foundation paper only allows for a max of a C (wanker teachers wouldnt allow me to do the higher paper_=)

[rtpb5642]

for the first one expand the brackets then multiply out the fractions and simplify

[cortexcortex]

80x^2/3 + 116x/3 + 56/3 + 3/x

4x^3√2x-3 + 3x√2x-3

2x(x-1)^1/2