2 Unit Revising Marathon (3 Viewers)

[powlmao]

Re: 2 Unit Revising Marathon HSC '10

More questions!

 

[MrBrightside]

Re: 2 Unit Revising Marathon HSC '10

Solve: |x -5| = 3

 

[powlmao]

Re: 2 Unit Revising Marathon HSC '10

Solve: |x -5| = 3

Easy

|x - 5 | =3

Part one

x-5=3
x=8

Part two

x-5=-3
x=2

Therefore x= 2, 8

 

[powlmao]

Re: 2 Unit Revising Marathon HSC '10

Easy

|x - 5 | =3

Part one

x-5=3
x=8

Part two

x-5=-3
x=2

Therefore x= 2, 8

More?

 

[MrBrightside]

Re: 2 Unit Revising Marathon HSC '10

Easy

|x - 5 | =3

Part one

x-5=3
x=8

Part two

x-5=-3
x=2

Therefore x= 2, 8

correct, you know this question on maths online, is taught the incorrect way. I saw it today and was like woah that's the wrong way, and its up there on maths online. They changed +- on the end number. Like you did.

I prefer this though:

x-5 = 3

OR​

-(x-5) = 3​

x = 8

OR​

-x + 5 = 3
-x = -2
x = 2​

Therefore x = 2 or x = 8

Both ways work, but I've been told that doing it the way I did it solves confusion when people do the other way.

 

[MrBrightside]

Re: 2 Unit Revising Marathon HSC '10

Find the integral of sec^2(5x) dx

 

[powlmao]

Re: 2 Unit Revising Marathon HSC '10

correct, you know this question on maths online, is taught the incorrect way. I saw it today and was like woah that's the wrong way, and its up there on maths online. They changed +- on the end number. Like you did.

I prefer this though:

x-5 = 3

OR​

-(x-5) = 3​

x = 8

OR​

-x + 5 = 3
-x = -2
x = 2​

Therefore x = -2 or x = 8

Both ways work, but I've been told that doing it the way I did it solves confusion when people do the other way.

When using absolute values x is always greater than zero otherwise you will get

| x - 5 |

sub -2 in

| -2 - 5 |

= |-7 |
=7
and 7 isn't equal to 3

Looking at your answer again, i believe you just made a typo

 

[MrBrightside]

Re: 2 Unit Revising Marathon HSC '10

When using absolute values x is always greater than zero otherwise you will get

| x - 5 |

sub -2 in

| -2 - 5 |

= |-7 |
=7
and 7 isn't equal to 3

Looking at your answer again, i believe you just made a typo

ahh yeah sorry typo sorry. Fixed.

 

[artosis]

Re: 2 Unit Revising Marathon HSC '10

Find the integral of sec^2(5x) dx

using the standard integral sheet:

= 1/5 tan 5x

 

[powlmao]

Re: 2 Unit Revising Marathon HSC '10

ahh yeah sorry typo sorry. Fixed.

haha it is fine

Maths isn't easy to type on computers.

New one

A function ƒ(x) is defined by ƒ(x) =2x2(3– x).
(i)
Find the coordinates of the turning points of y =ƒ(x) and determine their nature.
(ii)
Find the coordinates of the point of inflexion.
(iii) Hence sketch the graph of y =ƒ(x), showing the turning points, the point of inflexion and the points where the curve meets the x-axis.
(iv) What is the minimum value of ƒ(x) for –1 ≤x ≤4?

 

[MrBrightside]

Re: 2 Unit Revising Marathon HSC '10

=

Did you use PSF method?

 

[MrBrightside]

Re: 2 Unit Revising Marathon HSC '10

using the standard integral sheet:

= 1/5 tan 5x

correct, but you forgot to + C as it is indefinite.

 

[SpiralFlex]

Re: 2 Unit Revising Marathon HSC '10

using the standard integral sheet:

= 1/5 tan 5x

Calculate the exact volume formed by the curve bounded by the lines and .

 

[powlmao]

Re: 2 Unit Revising Marathon HSC '10

Did you use PSF method?

Observation.

PSF is weird to use IMO

 

[MrBrightside]

Re: 2 Unit Revising Marathon HSC '10

haha it is fine

Maths isn't easy to type on computers.

New one

A function ƒ(x) is defined by ƒ(x) =2x2(3– x).
(i)
Find the coordinates of the turning points of y =ƒ(x) and determine their nature.
(ii)
Find the coordinates of the point of inflexion.
(iii) Hence sketch the graph of y =ƒ(x), showing the turning points, the point of inflexion and the points where the curve meets the x-axis.
(iv) What is the minimum value of ƒ(x) for –1 ≤x ≤4?

Do you multiply that to become 4x? Or do you just treat it as u = 2x , v = 2(3-x)

 

[powlmao]

Re: 2 Unit Revising Marathon HSC '10

Sorry it is meant to be f(x) = 2x^2 (3-x)

I copied it straight from a past paper.

 

[SpiralFlex]

Re: 2 Unit Revising Marathon HSC '10



i.

For stationary points,

Hence,







When

When



At

Hence is a minimum turning point.

At

Hence, is a maximum turning point.


ii. For possible points of inflexion,





When

As

As

Hence a change of concavity has occurred, so is a point of inflexion.


iii. Cannot draw as we are online.


iv. When

When

Minimum value is .

This one is quite interesting for 2U students,

Calculate the exact volume formed by the curve bounded by the lines and .

 

[powlmao]

Re: 2 Unit Revising Marathon HSC '10

Wouldn't have a clue how to start that one.

 

[SpiralFlex]

Re: 2 Unit Revising Marathon HSC '10

Wouldn't have a clue how to start that one.

Think deeply.

 

[powlmao]

Re: 2 Unit Revising Marathon HSC '10

Think deeply.

My school is only up to functions! (We have done barely anything)

Other than that I just know most of Trig, intergration, differeniation and probability