Help with Functions, Limits etc.,

1. If f(x) = \lim_{x\rightarrow \infty } \frac{1}{1+nsin^{2}\pi x} , find f(x) for all real values of x.

2. 2f(x) + f(-x) = 1+x, find f'(10).

3. If a,b,c are in GP such that a+b+c = bx. Find all x satisfying the above relation.

13 Answers

21
Shubhodip ·

2)2f(x) + f(-x) = 1+x

2f(-x) + f(x) = 1-x

now solve for f(x)

1708
man111 singh ·

$(3) Let $b=ar$ and $c=ar^2.$ Where $-1<r<1$.Then\\\\ $a+ar+ar^2=ar.x\Leftrightarrow 1+r+r^2=rx$\\\\ $r^2+r(1-x)+1=0.$\\\\ Now solve The Quadratic equation Where $-1<r<1$

71
Vivek @ Born this Way ·

@ Subho.. Thanks got it.
@man111 .. Got it!

71
Vivek @ Born this Way ·

Q:=> Find all integers n1,n2 satisfying n1n2 = 2n1-n2

Q:=> Find the locus of (3secθ,4cotθ) where θ varies.

1
kunl ·

aa....-1<r<1 ? why?

71
Vivek @ Born this Way ·

heellppp

1
bindaas ·

LoCus
x2=9(1+16y2)

23
qwerty ·

n1n2 = 2n1-n2

implies 2= (n1+1) (2-n2)

now use the arguement that both are integers

71
Vivek @ Born this Way ·

Hmm.. Ok.. and the first one?

1
Aniket Ghosh Dastidar ·

In the first sum are you sure it is x→∞ and not n→∞..??

71
Vivek @ Born this Way ·

I think it is.. !!

1
Aniket Ghosh Dastidar ·

if its n→∞.
Then the limit wud give 1 for all integral values of x as nSin2\PiX wud be =0..
T all other values of x limit wud be =0 as denominator is ∞

11
Joydoot ghatak ·

n1n2=2n1-n2.

thus,n2(n1+1)2 =n1.

thus,n2 =2n1n1+1.

n2= 2 - 2n1+1.

n1 can take values 1, 0, -2 and -3 otherwise n2 becomes a fraction.

the answer is 4??

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