Functions (1 Viewer)

[lyounamu]

Sorry, I didn't see the 'square root' thing. Yes, continuum's one is right.

 

[lyounamu]

f(x) = sqrt(x^2+2x-3)
Anything inside a square root sign must be greater than or equal to zero. Hence:
x^2+2x-3 >= 0
(x+3)(x-1) >= 0
x <= 3 and x >= 1

y <=-3 by the way. Otherwise it's perfectly right.

 

[adidasboy]

How do you draw a square root symbol on computer?

 

[kurt.physics]

on a mac it is: option + v

on a pc: i would imagine its alt + v


where i have put a plus, it means at the same time, you can hold down alt and then press v but alt must be down aswell.

 

[Sew2289]

Hey guys can somebody kindly help me with the answer to this?

if F(x)=X^2+3x

Find in simplest form

f(x+h)-f(x)
h

I tried to figure it out, don't know if I did it right though.

Thanks.

 

[lyounamu]

Hey guys can somebody kindly help me with the answer to this?

if F(x)=X^2+3x

Find in simplest form

f(x+h)-f(x)
h

I tried to figure it out, don't know if I did it right though.

Thanks.

Answer is 2x + h +3

EDIT: Are you doing the first principle of derivative? Then you should put the limit sign as well (if not, don't worry).

FURTHER EDITION: If you need my working out, I will post it up.

 

[Sew2289]

No we havent done derrivatives yet (Im term 2 year 11, I know my profile says 2008). I didnt somehow get the h in my answer I only had 2x+3. How did you work out your answer?

 

[lyounamu]

No we havent done derrivatives yet (Im term 2 year 11, I know my profile says 2008). I didnt somehow get the h in my answer I only had 2x+3. How did you work out your answer?

My working out is like the followings:

f(x) = x^2 +3x / h
Then f(x+h) = (x+h)^2 + 3(x+h)
= x^2 +2hx + h^2 +3x +3h

Therefore, f(x+h) - f(x) / h = x^2 +2hx+h^2 +3x +3h-(x^2 + 3x)/h
= x^2 +2hx +h^2 +3x +3h -x^2 -3x /h
= 2xh + h^2 +3h /h
= 2x + h +3

 

[tommykins]

Turns out to be 2x + h + 3.
EDIT : let me actually do it.

 

[lyounamu]

It should only be 2x+3, the h cancels out.

That's differentiating from first principles, there shouldn't be a h.

EDIT : let me actually do it.

I know, but he is not doing this from the first derivative.

 

[kurt.physics]

Hey guys can somebody kindly help me with the answer to this?

if F(x)=X^2+3x

Find in simplest form

f(x+h)-f(x)
h

I tried to figure it out, don't know if I did it right though.

Thanks.

f(x+h) = (x+h)² + 3(x+h)
= x² + 2hx + h² + 3x + 3h


f(x) = x² + 3x

f(x+h) - f(x) = x² + 2hx + h² + 3x + 3h - (x² + 3x)

= x² + 2hx + h² + 3x + 3h -x² - 3x
= h² + 2hx + 3h


f(x+h)-f(x) = (h² + 2hx + 3h) ÷ h
h
= (h(h+2x+3)) ÷ h

= h + 2x + 3

 

[Sew2289]

My working out is like the followings:

f(x) = x^2 +3x / h
Then f(x+h) = (x+h)^2 + 3(x+h)
= x^2 +2hx + h^2 +3x +3h

Therefore, f(x+h) - f(x) / h = x^2 +2hx+h^2 +3x +3h-(x^2 + 3x)/h
= x^2 +2hx +h^2 +3x +3h -x^2 -3x /h
= 2xh + h^2 +3h /h
= 2x + h +3

Cheers Mate, your like a bullet at replying, top stuff!

 

[adidasboy]

√ oh its alt 251
Googled it lol.
looks more like a tick than square root

 

[tommykins]

I know, but he is not doing this from the first derivative.

Yeah fixed it when I actually did the q.

 

[Continuum]

No we havent done derrivatives yet (Im term 2 year 11, I know my profile says 2008). I didnt somehow get the h in my answer I only had 2x+3. How did you work out your answer?

It's funny how you got the answer 2x+3, since that's the answer if you approached the question using differentiation.

 

[lyounamu]

It's funny how you got the answer 2x+3, since that's the answer if you approached the question using differentiation.

May be he thought that we were using the first derivative where we have limit sign where h approaching 0. Then, we have 2x +h +3 where h becomes 0, which becomes 2x +3.

 

[cherry1991]

Functions Assignment

The scientist Galilea discovered that the period of a pendulum(the time for one complete swing) is a function of its length
a) use function notation to express this statment
i think its f(L)=t ?

b. An approximate model for the motion of a pendulum is that the period (in seconds) is twice the square root of the lenth ( in metres). Write this model as an algebraic formula
T=2 square root L ?
Calculate a few values of the function and sketch its graph
so what kinda graph? like i know i put different lengths and get different times but i duno how to sketch it
So length 4 the period of time would be: 4 seconds
length 16 the period of time would be: 8 seconds

d. if u have 2 pendulums, with the length of one four times the length of the other, how will their periods compare? Write your answer using function notationNEED HELP WITH THIS QUESTION