n00b needs help with 4 easy questions! help plz (1 Viewer)

[thejagman]

can someone please give me answers to the following (i am really bad at maths) with working intended for a complete n00b? i would really appreciate it!
i cant seem to understand anything my teacher says and i am waiting for new textbooks to arrive to explain these topics a bit more.

1. differentiate

x R(x+1)

R denotes the root sign, with (x+1) being under/in it

2. The roots of a monic polynomial of degree 3 are 1, -1 and 3. Find the equation of the polynomial.

3. Given that sinA = 4/5, where 90d < A< 180d, find the exact value of sin2A.

'd' is degrees btw.

4. solve the equation cos2 (T) = 2sin^2 (T) for 0d \< (T) \< 360d

'd' is degrees. (T) is Theta '^2' is squared. '\<' is less than or equal to.

Thanks for your help! if you dont wnat to do all 4, just do 1 (if you even want to help me) and hopefully someone else might do another etc.

 

[FinalFantasy]

hahaha i like it how u use the word "n00b"
u play CS or some strategy game or something?

1. "differentiate

x R(x+1)"

d\dx xsqrt(x+1)=1*sqrt(x+1)+1\2(x+1)^(-1\2) * x
=sqrt(x+1)+x\2sqrt(x+1)

"2. The roots of a monic polynomial of degree 3 are 1, -1 and 3. Find the equation of the polynomial."

to find the equation just expand: (x-1)(x+1)(x-3)

"3. Given that sinA = 4/5, where 90d < A< 180d, find the exact value of sin2A.

'd' is degrees btw."
sin2A=2sinAcosA
just draw the diagram den u know cosA
den put it in...

"4. solve the equation cos2 (T) = 2sin^2 (T) for 0d \< (T) \< 360d

'd' is degrees. (T) is Theta '^2' is squared. '\<' is less than or equal to."

cos2t=2sin²t
2(1-cos²t)-cos2t=0
2-2cos²t-cos2t=0
2-2cos²t-(2cos²t-1)=0
2-4cos²t+1=0
so 4cos²t=3
cos²t=3\4
cos t=+-root 3 \2
t=pi\6, 5pi\6, 7pi\6, 11pi\6

 

[thejagman]

thank you so much! yes i do play CS, but i play RuneScape these days a bit more. i am not a n00b to these, but am referred to as one because of my lack of talent in computer games in general

 

[FinalFantasy]

"thejagman
New Member


HSC: 2008
Gender: Male"
HSC 2008?????????
so ur in year 9?????
and ur doing this already?

 

[thejagman]

i am in year 10... i prob wasnt thinking when i put in 2008 i just wanted the registration finished

there was only one student doing it this year the head maths teacher asked our advanced 10 class if anyone that is thinking about doing it next year wants to do it now so as to get a bit of a headstart for next year. i can do some things quite good but im having a hard time with most things.

thx again for ur answers by the way. and u did them so quickly
hope i will be on ur level in a year or 2

 

[haboozin]

i remember i did a bit of polynomials in yr 10 in advanced maths, i thought they were the hardest thing ever..

now i think polynomial is almost the easiest topic in maths especially 4unit poly is so simple.

So yea, you do get better haha.

 

[withoutaface]

I couldn't factorise a trinomial until mid term 1 of year 10.

 

[rama_v]

I couldn't factorise a trinomial until mid term 1 of year 10.

I couldnt complete the square until term 1 yr 11 lol

 

[Jago]

I couldn't factorise a trinomial until mid term 1 of year 10.

i can still only barely factorise trinomials