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Re: Nairaland Mathematics Clinic by Nobody: 12:55pm On Nov 30, 2013
Mr Calculus: plz my generals i need ur help to dis o.@laplacian,rechiez,ben,fx,smurfy,ortarico.e.t.c
i dont know but d answers to d ques are 16.78' & 31.1'.
plz i want d workings not only d answers

The solution is so long that it's possible I made a mistake somewhere.
Re: Nairaland Mathematics Clinic by Humphrey77(m): 1:50pm On Nov 30, 2013
if 3 raise to power 1998 is divided by 5 what is the remainder
Re: Nairaland Mathematics Clinic by Nobody: 1:58pm On Nov 30, 2013
Mr Calculus: plz my generals i need ur help to dis o.@laplacian,rechiez,ben,fx,smurfy,ortarico.e.t.c
i dont know but d answers to d ques are 16.78' & 31.1'.
plz i want d workings not only d answers

@ = 28.1, ¥ = 14.9

I'm pretty sure the answer above is correct.

3sin2@ = 5sin2¥ (eqn 1)
tan@ = 2tan¥ (eqn 2)

(1) divided by (2) gives:

6cos^2@ = 5sin^2¥ (eqn 3)

From (1),
6sin@cos@ = 10sin¥cos¥ (eqn 4)

Squaring (4) and changing all to sine gives:

36sin^2@ - 36sin^4@ = 100sin^2¥ - 100sin^4¥ (eqn 5)

From (3), sin^2¥ = (5 - 6cos^2@)/5 (eqn 6).

Slot (6) into (5) to get 108sin^4@ - 132sin^2@ + 24 = 0

I used Microsoft Maths to solve the corresponding equation
108x^4 - 132x^2 + 24 = 0 to get x = sqrt(2)/3 or 0.471404.... [I ignored the other values of x, namely -0.471404..., -1 and 1.]

This implies sin@ = 0.471404....

@ = 28.1. Slot this into (2) to get ¥ = 14.9.
Re: Nairaland Mathematics Clinic by Laplacian(m): 2:19pm On Nov 30, 2013
Mr Calculus: plz guys help me out wit dis......
if 3sin2@=5sin2¥....
find @ & ¥ if(tan@=2tan¥)
3*2sin@cos@=5*2sin¥cos¥
and
sin@/cos@=2sin¥/cos¥....
Multiply&divide both eqns respectively;
3sin^2@=10sin^2¥
and
3cos^2@=2.5cos^2¥
add both equatns;
3=10sin^2¥+2.5cos^2¥
or
3=7.5sin^2¥+2.5
or
0.5=7.5sin^2¥
or
1=15sin^2¥
or
sin¥=sqr(1/15)
from there u can find ¥ and @
Re: Nairaland Mathematics Clinic by Nobody: 2:30pm On Nov 30, 2013
Laplacian:
3*2sin@cos@=5*2sin¥cos¥
and
sin@/cos@=2sin¥/cos¥....
Multiply&divide both eqns respectively;
3sin^2@=10sin^2¥
and
3cos^2@=2.5cos^2¥
add both equatns;
3=10sin^2¥+2.5cos^2¥
or
3=7.5sin^2¥+2.5
or
0.5=7.5sin^2¥
or
1=15sin^2¥
or
sin¥=sqr(1/15)
from there u can find ¥ and @

Yeah. sin¥ = sqrt(1/15) gives ¥ = 14.9 and @ = 28.1.

That's exactly what I got above.
Re: Nairaland Mathematics Clinic by Laplacian(m): 2:32pm On Nov 30, 2013
Humphrey77: if 3 raise to power 1998 is divided by 5 what is the remainder
4

1 Like

Re: Nairaland Mathematics Clinic by Humphrey77(m): 2:33pm On Nov 30, 2013
sin2x+sinx is equal to 1 we know that sin2x is equal to 2sinxcosx. clearly; we have 2sinxcosx +sinx equal to 1 . so let sinx equal to y; by subtitution into

sin2x + sinx equal to 1 we obtain the equation: 4y"4-3y"2-2y+1 equal to zero ; by solving for y we obtain y equal to 1; clearly recall that sinx is equal to y so we have x eq
ual to arcsin(1) we have x equal to 90 so x is equal to 90

1 Like

Re: Nairaland Mathematics Clinic by Nobody: 2:40pm On Nov 30, 2013
Humphrey77: if 3 raise to power 1998 is divided by 5 what is the remainder
Re: Nairaland Mathematics Clinic by Humphrey77(m): 2:40pm On Nov 30, 2013
@ lapacian show it
Re: Nairaland Mathematics Clinic by Nobody: 2:43pm On Nov 30, 2013
Humphrey77: if 3 raise to power 1998 is divided by 5 what is the remainder

Huh?
Re: Nairaland Mathematics Clinic by Laplacian(m): 2:46pm On Nov 30, 2013
Humphrey77: @ lapacian show it
i will not show it because my method of solution is always "INCORRECT"...use modular arithmetic

1 Like

Re: Nairaland Mathematics Clinic by Humphrey77(m): 2:51pm On Nov 30, 2013
this is number theory sir ! by fermart eluer theorm
Re: Nairaland Mathematics Clinic by jackpot(f): 3:02pm On Nov 30, 2013
Humphrey77: if 3 raise to power 1998 is divided by 5 what is the remainder
Laplacian:
4
If you're not cleared as to how the answer above is gotten, note that for any natural number n,

34n=(34)n = 81n = 10M+1, for some integer M.

Similarly,
34n+1=3(34n)=30M+3
34n+2=32(34n)=90M+9
34n+3=33(34n)=270M+27.

Observe that 31998 can be written as 34n+2, where n=499.

Now, for some integer M,

31998=34n+2=90M+9=18(5)M+(5+4)=5(18M+1)+4.

From, the last equation, it is obvious why 3 raised to power 1998 leaves a remainder of 4 when divided by 5.

Gracias.
Re: Nairaland Mathematics Clinic by Humphrey77(m): 3:10pm On Nov 30, 2013
2"h + 3"h is equal 5"h here it goes (5-3)"h + (5-2)"h _-5"h by linear approx i.e 5"h(1-3h/5)+5"h(1-2h/5)_-5"h we have 1-3h/5+1-2h/5-_1 clearly h-_1
Re: Nairaland Mathematics Clinic by Nobody: 3:26pm On Nov 30, 2013
@ Humphrey77

Always quote the question you're trying to solve.
Re: Nairaland Mathematics Clinic by Humphrey77(m): 3:37pm On Nov 30, 2013
Humphrey77: if ,m and n are open set than show that the intersection is also open
































@ laplacian







Re: Nairaland Mathematics Clinic by MrCalculus(m): 4:25pm On Nov 30, 2013
smurfy:

Yeah. sin¥ = sqrt(1/15) gives ¥ = 14.9 and @ = 28.1.

That's exactly what I got above.
THANKS SMURFY & LAPLACIAN
Re: Nairaland Mathematics Clinic by Laplacian(m): 4:49pm On Nov 30, 2013
[quote author=Humphrey77][/quote]
guy am stil an amatur ooo, (not yet a topologist)..
Let a<m<A and b<n<B denot d two open sets...
suppos, on d contrary, dat their intersection, p, is a closed set...
Then we can find x and y such dat
x<=p<=y, where a, b<x and y<A, B
now suppose, without loss of generality, dat A<B....then we can always find d numbers z such dat
y<z<A, since z<A<B, z should b in their intersection, but y<z a contradiction, showing dat z is not in their intersection...hence our supposition dat p is a closed set is untenable....and d result follows
Re: Nairaland Mathematics Clinic by Nobody: 5:04pm On Nov 30, 2013
Hmmm.
Re: Nairaland Mathematics Clinic by Laplacian(m): 6:56pm On Nov 30, 2013
Humphrey77: sin2x+sinx is equal to 1 we know that sin2x is equal to 2sinxcosx. clearly; we have 2sinxcosx +sinx equal to 1 . so let sinx equal to y; by subtitution into

sin2x + sinx equal to 1 we obtain the equation: 4y"4-3y"2-2y+1 equal to zero ; by solving for y we obtain y equal to 1; clearly recall that sinx is equal to y so we have x eq
ual to arcsin(1) we have x equal to 90 so x is equal to 90
solvin d differential eqn u cannot get y=1,
suppose y=1, indeed y'=0, y"=0,
substitute into ur differential eqn,
4y"4-3y"2-2y+1=0 to obtain

0-0-2+1=0
or
-1=0

hw did u solve ur differential eqn?
Re: Nairaland Mathematics Clinic by jackpot(f): 7:17pm On Nov 30, 2013
Laplacian:
guy am stil an amatur ooo, (not yet a topologist)..
Let a<m<A and b<n<B denot d two open sets...
suppos, on d contrary, dat their intersection, p, is a closed set...
Then we can find x and y such dat
x<=p<=y, where a, b<x and y<A, B
now suppose, without loss of generality, dat A<B....then we can always find d numbers z such dat
y<z<A, since z<A<B, z should b in their intersection, but y<z a contradiction, showing dat z is not in their intersection...hence our supposition dat p is a closed set is untenable....and d result follows
Hi Sir Laplacian

how can a set be less than or equal to a point x?
Re: Nairaland Mathematics Clinic by Laplacian(m): 7:55pm On Nov 30, 2013
jackpot: Hi Sir Laplacian

how can a set be less than or equal to a point x?
sorry, i was tryin 2 avoid lengthy computations, i tot everybdy 'll undstnd.
put mathematically,
the set
P={p : x<=p<=y},

M={m : a<m<A},

N={n : b<n<B}.

Z={ z: y<z<A},

NB: z=(y+A)/2€Z
Every other thing remains the same
Re: Nairaland Mathematics Clinic by jackpot(f): 9:15pm On Nov 30, 2013
^you are assuming that all your sets are subsets of IR, the set of real numbers and you are also assuming that elements can be compared by your use of less than sign. ( < )

my question is, what if the sets are open in R2? Or what if they are domains in the Complex Plane?

Can your proof work for an arbitrary open set?
Re: Nairaland Mathematics Clinic by Humphrey77(m): 9:53pm On Nov 30, 2013
Laplacian:
solvin d differential eqn u cannot get y=1,
suppose y=1, indeed y'=0, y"=0,
substitute into ur differential eqn,
4y"4-3y"2-2y+1=0 to obtain

0-0-2+1=0
or
-1=0

hw did u solve ur differential eqn?
@ LAPLACIAN SIR THE SIGN " ,,MEANS RAISE TO POWER NOT A DIFFERENTIAL EQUATION
Re: Nairaland Mathematics Clinic by Humphrey77(m): 9:59pm On Nov 30, 2013
[quote author=Humphrey77] the sign("wink means raise to power
Re: Nairaland Mathematics Clinic by Humphrey77(m): 10:03pm On Nov 30, 2013
jackpot: Hi Sir Laplacian

how can a set be less than or equal to a point x?
YOU TRY AM NOT OK WITH YOUR PROOF
Re: Nairaland Mathematics Clinic by Humphrey77(m): 10:25pm On Nov 30, 2013
jackpot: If you're not cleared as to how the answer above is gotten, note that for any natural number n,

34n=(34)n = 81n = 10M+1, for some integer M.

Similarly,
34n+1=3(34n)=30M+3
34n+2=32(34n)=90M+9
34n+3=33(34n)=270M+27.

Observe that 31998 can be written as 34n+2, where n=499.

Now, for some integer M,

31998=34n+2=90M+9=18(5)M+(5+4)=5(18M+1)+4.

From, the last equation, it is obvious why 3 raised to power 1998 leaves a remainder of 4 when divided by 5.

Gracias.
good work! BUT U NEED TO GO AND STUDY YR NUMBER THEORY VERY WELL
Re: Nairaland Mathematics Clinic by Humphrey77(m): 10:30pm On Nov 30, 2013
Laplacian:
guy am stil an amatur ooo, (not yet a topologist)..
Let a<m<A and b<n<B denot d two open sets...
suppos, on d contrary, dat their intersection, p, is a closed set...
Then we can find x and y such dat
x<=p<=y, where a, b<x and y<A, B
now suppose, without loss of generality, dat A<B.... we can always find d numbers z such dat
y<z<A, since z<A<B, z should b in their , but y<z a contradiction, showing dat z is not in their intersection...hence our supposition dat p is a set is untenable....and d result follows
WRONG SIR
Re: Nairaland Mathematics Clinic by jackpot(f): 12:25am On Dec 01, 2013
Humphrey77: good work! BUT U NEED TO GO AND STUDY YR NUMBER THEORY VERY WELL
This guy, e be like say u snuff a little alcohol, bah? Why are u quoting people and replying nonsense? I drafted a solution that will convince even non-mathematicians on how the answer is gotten. I am not a stereotyped mathematician.

A mere 5 seconds look at the question, I pictured the answer. Integral powers of 3 ends with the cycle of digits {3, 9, 7, 1}.



1998Mod4=2

and 3 raised to power of the residue class of 2 yields 9.

and 9Mod5=4.

Maybe thats how you want the solution to look like?

SMH.

1 Like

Re: Nairaland Mathematics Clinic by jackpot(f): 1:25am On Dec 01, 2013
Humphrey77: sin2x+sinx is equal to 1 we know that sin2x is equal to 2sinxcosx. clearly; we have 2sinxcosx +sinx equal to 1 . so let sinx equal to y; by subtitution into

sin2x + sinx equal to 1 we obtain the equation: 4y4-3y2-2y+1 equal to zero ; by solving for y we obtain y equal to 1; clearly recall that sinx is equal to y so we have x equal to arcsin(1) we have x equal to 90 so x is equal to 90
Sweetheart, I am sorry to burst your bubbles but your answer is regrettably very myopic and careless. For you to see what I meant,

4y4-3y2-2y+1=(y-1)(4y3+4y2+y-1)
This is a quartic equation with four roots: 2 real and 2 complex conjugate roots.

The real roots are y=1 and y=0.347810385. . .
Now, for y=1,
sin x=1 --> x= sin-1(1)=90 + 360k, where k is an integer.
i.e., x={. . .-630,-270,90,450,810,. . .}.
Clearly this is an infinite set of solutions for x.


Next, for y=0.347810385. . .,
x=sin-1(0.347810385. . .)=20.35344681+360k, where k is an integer.
This also yields an infinite set of solutions.

For the other 2 complex roots of y, complex solutions of x exists, but i will stop here, since the person that posed the question was probably expecting only real solutions.



So, dear Humphrey, if I should score your solution,

As an SS1 student, I'll score you 75%.

As an SS3 student, I'll score you 50% because you failed to get the other real solution of y.

As a year one student, I'll score you 40%. #LetMyPeopleGoThings# tongue cheesy

As a final year student, na 0% for sure, since the number of solutions for x (in order to get the full marks) is infinite, and you merely provided one.
See how I arrived at your score:
1/infinity * 100%=0% tongue tongue tongue

1 Like

Re: Nairaland Mathematics Clinic by Laplacian(m): 8:06am On Dec 01, 2013
jackpot: ^you are assuming that all your sets are subsets of IR, the set of real numbers and you are also assuming that elements can be compared by your use of less than sign. ( < )

my question is, what if the sets are open in R2? Or what if they are domains in the Complex Plane?

Can your proof work for an arbitrary open set?
@Humphry, i suggest u & Benbuks should always provide d incorrect steps in any wrong solutions like jackpot alwaz does and myselt too, not 2 simply dismis it & leave d solver in doubt&confusion...even if my solution does not cover d general case, it has @ least settled d case pointed out by jackpot abov....and dat should worth some apprreciation...
u 'r modest lady jackpot & i like ur styl of criticism....i 've not really wrked on provin d general case though, but i 'll giv it a second thought now that u hav underlined it...but i know it will hav 2 incoperate d NORM and follow a similar chain of reasonin as abov....by d way, wat's preventin u from supplying a proof? Or 're u just watchin 4rm d sidelines just 2 handpick my errors?....
@ALL, am not here 2 enter into competition wit anybdy, 4 those dat copy questions (witout havin challenges wit them) from textbooks & paste here.....i'll only attempt questions only by individuals who hav difficulties wit them & are genuinely desperate 4 their solution...
Re: Nairaland Mathematics Clinic by Humphrey77(m): 9:18am On Dec 01, 2013
jackpot: This guy, e be like say u snuff a little alcohol, bah? Why are u quoting people and replying nonsense? I drafted a solution that will convince even non-mathematicians on how the answer is gotten. I am not a stereotyped mathematician.

A mere 5 seconds look at the question, I pictured the answer. Integral powers of 3 ends with the cycle of digits {3, 9, 7, 1}.



1998Mod4=2

and 3 raised to power of the residue class of 2 yields 9.

and 9Mod5=4.

Maybe thats how you want the solution look like?

SMH.
good dear

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