the equation in question is 3sin(x+3)=cos(2x) to 4 dp between 0 =< x =< 7
by rearranging the equation i get f(x) = 3sin(x+3)-cos(2x) which im sure is correct as this is what i get in maple and calculus bagatirx
next step is to check by basically guess
so I guess 3.5 which is -0.10854 and 3.75 is 1.0034 so i think ok jackpot I'm close enough
anyway I differentiate it to 3COS(x+3) + 2sin(2x)
I then calculator using general iteration formula which is xnew= x(-0.10854) - f(x)/f'(x)
I run this continually until i get -0.1765 and this is what the newton-raphson calculator online confirms it as
my book states the answer is 3.524 and 6.1067 I MEAN WTF IS THAT??!! is my answer wrong, am I doing something wrong?
or is my book full of **** (which it has been lately, alot of stuff is incorrect but I can't rule it out that I haven't made a mistake or whether the fact the book is wrong)
I think there's a root at -0.1765, although that root isn't in the domain 0 ≤ x ≤ 7. I got 6.1067, but not 3.524. I don't understand how you can have two values, so I too am confused by your textbook. o.o
The book is correct mate. Go over your working again.
ok i figured it out, i was using the wrong value for x when it came to using the iteration formula
You need to do 3.5-F(3.5)/F'(3.5) to begin with. Then go from there.
Thanks for posting! You just need to create an account in order to submit the post
Already a member?
Oops, something wasn't right
please check the following:
Not got an account?
Sign up now
© Copyright The Student Room 2015 all rights reserved
The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.
Register Number: 04666380 (England and Wales), VAT No. 806 8067 22
Registered Office: International House, Queens Road, Brighton, BN1 3XE