[member592149]

Can someone explain why it is root 7 and -3, rather than root 7 and positive 3 in 2008. Paper 2. Question 3.

[benten17]

(Original post by JaggySnake95)
Can someone explain why it is root 7 and -3, rather than root 7 and positive 3 in 2008. Paper 2. Question 3.

Normally a sin graph goes from 0 up to 1 down to 0 down to -1 and back up to 0, those are y values. This graph goes down then up then up then down. If it were positive 3 it would follow the former pattern so it can't be. A negative in front of the sin will flip a sin graph across the x axis, ie make it go down the up...
Therefore we need -3

[member592149]

(Original post by benten17)
Normally a sin graph goes from 0 up to 1 down to 0 down to -1 and back up to 0, those are y values. This graph goes down then up then up then down. If it were positive 3 it would follow the former pattern so it can't be. A negative in front of the sin will flip a sin graph across the x axis, ie make it go down the up...
Therefore we need -3

That's what I thought but surely the root 7 should be negative then?

[Bonzo10]

(Original post by JaggySnake95)
That's what I thought but surely the root 7 should be negative then?

I just negative repped you by mistake when I meant to hit quote on my stupid iPhone. Sorry! Dunno how to undo.

Also, the root7 graph is a cos graph which normally starts at 1 anyway?

[StudyAk]

Good luck Everyone. Hope it goes good!

[Blue7195]

woke up bright eyed and bushy tailed, got a good feeling today this is going to be a nice paper! they can't put us through the torture from that credit exam from last year and a hard exam this year?! haha good luck everyone!

[lozza.22]

Good luck today everyone! Bit nervous but sure everyone will do fine!!


This was posted from The Student Room's iPhone/iPad App

[Blue7195]

just as short revision, when then the roots are real, irrational if say , and rational if ? then, if then the roots are equal, and if then the roots are not real, unequal, ah good remembered !

[member592149]

Up at 8 for a couple past papers and reminding myself of some of my notes.

[Revolver72]

Best of luck today, all

[rawragee]

I tried to do a supposedly nice past paper to get me in a mathematical mindset I guess, then started crying because I couldn't do the first steps of an 8 marker.. awh that's a good omen!

Good luck today everybody, we've all worked hard enough!

[TheRedGoldfish]

(Original post by Blue7195)
just as short revision, when then the roots are real, irrational if say , and rational if ? then, if then the roots are equal, and if then the roots are not real, unequal, ah good remembered !

Remember that when working out complicated roots you are square rooting b^2 - 4ac

In 2011 at least, the discriminant = 23, in other words b^2 - 4ac = 23 and since it's greater than 0 then there will be two real roots

When it equals 0 there is one equal root and if it's less then there will be no real roots



And if a surd still remains even after simplifying then yes it's irrational and if it can eventually be broken down into whole numbers then it is rational

[Blue7195]

okay please cn someone help me?!

[Blue7195]

with this? ahhhh

[Herzschmerz]

You need to put the two equations equal to each other and solve to find x.

[auberjean]

(Original post by Blue7195)
with this? ahhhh

Start by setting the equations equal to each other and solve to find x.

[Blue7195]

(Original post by auberjean)
Start by setting the equations equal to each other and solve to find x.

i end up getting .. how do i solve this? synthetic doesn't work.. neither does diff..

[aroy45]

(Original post by Blue7195)
i end up getting .. how do i solve this? synthetic doesn't work.. neither does diff..

Make x=1 and do synthetic division

[Herzschmerz]

EDIT: The person above is right.

[Blue7195]

(Original post by aroy45)
Make x=1 and do synthetic division

thanks so much! seen it and was like ahhh... incase it came up today so freaked out a lil' :P