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Mathematics 9 Online
OpenStudy (firejay5):

*If I have anything wrong, please let me know, so I can learn from my mistake.* Part 1: Describe the change to the parent function (cubed root). Part 2: Create an equation based on the following transformations. *My Answer will be in a PDF File to be checked/graded.*

OpenStudy (firejay5):

OpenStudy (firejay5):

@campbell_st

OpenStudy (firejay5):

okay

OpenStudy (aum):

the rest looks good.

OpenStudy (firejay5):

so if it's f(x) = -4x^2 it's reflected over the y - axis

OpenStudy (aum):

Pardon me. I think I have made some mistakes here. I had it clearly in my mind and mistyped x and y. f(x) transformed to -f(x) is reflection over the x-axis f(x) transformed to f(-x) is reflection over the y-axis.

OpenStudy (firejay5):

could I write number 17. f(x) = -1/4 (x - 6)^3 + 2

OpenStudy (aum):

All of your answers looks correct (including #6 and #7).

OpenStudy (aum):

Oh, I have not seen the second page yet. All of your answers on page 1 looks correct.

OpenStudy (firejay5):

#10 is part of #'s 1-9

OpenStudy (aum):

#17) p(x) = x^3 (parent function) f(x) = - (1/4x - 6)^3 + 2 = -{ 1/4( x - 24) }^3 + 2 = -1/64 * (x - 24)^3 + 2 Shift right by 24 units, compress vertically by a factor of 64, reflect about the x-axis, shift vertically up by a factor of 2.

OpenStudy (firejay5):

does it have to be like: f(x) = - (1/4x -6)^3 + 2 or can it be -1/4(x - 6)^3 + 2

OpenStudy (aum):

The function that is given to you is f(x) = - (1/4x -6)^3 + 2 and NOT f(x) = -1/4(x - 6)^3 + 2. In transformations, if x is replaced by (x-a) we know that is a shift to the RIGHT by 'a' units. Here, we have a factor of 1/4 before x and so we can't say x is being replaced by (x-6). So we have to factor out the 1/4 which is what I did in my previous reply.

OpenStudy (firejay5):

read the transformations on the left side of the semicolon

OpenStudy (aum):

Oh, they are giving you the transformations and asking you for the function? I was doing problem 17 like problems 1-10 where f(x) is given and you have to describe the transformations. Let me do it the other way and check your answer.

OpenStudy (aum):

#17) Parent cubic function: x^3 Horizontal *compression* by a factor of 4: x^3 becomes (4x)^3. Reflection over x-axis: x becomes -x and so (4x)^3 becomes (-4x)^3. Shift right by 6 units: Replace x by (x - 6). So {-4(x-6)}^3. Shift up by 2 units: Add +2. So {-4(x-6)}^3 + 2.

OpenStudy (firejay5):

so f(x) = -4 (x - 6)^3 + 2

OpenStudy (aum):

oops, reflection over *x axis*: stick a negative sign in front of the function: (4x)^3 becomes -(4x)^3. Shift right by 6 units: Replace x by (x - 6). So -{4(x-6)}^3. Shift up by 2 units: Add +2. So -{4(x-6)}^3 + 2. In your previous reply the 4 should be included in the cubing.

OpenStudy (aum):

So the transformed function is: -{4(x-6)}^3 + 2 = -64(x-6)^3 + 2.

OpenStudy (firejay5):

so f(x) = - (4x - 6)^3 + 2

OpenStudy (aum):

Not quite. The x is replaced by (x-6) and so -(4x)^3 becomes -{ 4(x - 6) }^3. And then add 2.

OpenStudy (aum):

f(x) = -(4x - 24)^3 + 2 or f(x) = -64(x-6)^3 + 2

OpenStudy (firejay5):

do I really need to simplify it?

OpenStudy (aum):

It depends on what they are expecting. But to easily describe the transformations it would be better to leave it unsimplified at: f(x) = -{4(x-6)}^3 + 2.

OpenStudy (firejay5):

I just want the unsimplified answer that I give

OpenStudy (aum):

I am using curly brackets to indicate that 4 is getting cubed too.

OpenStudy (firejay5):

I appreciate that but it does get confusing when you use too many brackets, so do what I do, because we know the 4 will get cubed

OpenStudy (aum):

What is your answer? The one in the pdf file has 1/4 and so that is not correct.

OpenStudy (firejay5):

the ony I typed in the comments: f(x) = - (4x - 6)^3 + 2

OpenStudy (aum):

But the above function does NOT have a horizontal shift of 6. To have a horizontal shift of +6, x should be replaced by (x-6). But in your answer 4x is being replaced by 4x - 6 instead of 4(x-6).

OpenStudy (aum):

p(x) = -(4x)^3 + 2 f(x) = -(4x - 6)^3 + 2 f(x) is p(x) shifted to the right by 1.5 units and NOT 6 units because f(x) = -(4x - 6)^3 + 2 = -{ 4(x - 1.5) }^3 + 2. x in p(x) is being replaced by (x-1.5) and so it is a shift to the right by 1.5 units. But f(x) = -(4x - 24)^3 + 2 is p(x) shifted right by 6 units because f(x) = -(4x - 24)^3 + 2 = -{ 4(x - 6) }^3 + 2 where x in p(x) is being replaced by (x - 6).

OpenStudy (firejay5):

we don't use brackets for this we use the setup that I used: For example, f(x) = 3(x + 4)^3 - 6

OpenStudy (aum):

The final answer is: f(x) = -{4(x-6)}^3 + 2 If you don't like the curly brackets, then it is: f(x) = -(4x - 24)^3 + 2. Not your answer of f(x) = - (4x - 6)^3 + 2

OpenStudy (aum):

f(x) = -(4x - 24)^3 + 2 is shift to the right by 6 units. f(x) = -(4x - 6)^3 + 2 is shift to the right by 1.5 units.

OpenStudy (firejay5):

did you multiply 4 * 6 to get 24

OpenStudy (aum):

yes.

OpenStudy (firejay5):

I just assumed that if I put (4x - 6)^3 that it shifted to the right 6 units

OpenStudy (aum):

For positive 'a', f(x-a) shifts f(x) to the right by 'a' units. If a = 6, then f(x-6) shifts f(x) to the right by 6 units. If f(x) = x^2, then the right shifted function by 6 units is: f(x-6) = (x-6)^2 But if f(x) = 2x^2, then the right shifted function is f(x-6) = 2(x-6)^2 and NOT 2x^2 - 6.

OpenStudy (aum):

So if we start with the function f(x) = (4x)^3 and shift it to the right by 6 units it will become { 4(x-6) }^3 = (4x - 24)^3 and NOT 4x^3 - 6.

OpenStudy (firejay5):

I don't like brackets okay

OpenStudy (aum):

I started with the brackets to show you the steps involved but simplified it later, eliminating the brackets.

OpenStudy (aum):

For example, f(x) = (5x)^3. Shift the function to the right by 2 units. What will be the transformed function?

OpenStudy (firejay5):

I think I am clear on what #17 is talking about, so what about the 11 - 16

OpenStudy (aum):

#11: Since the parent is a cube root function, you need to insert a small 3 before the radical sign to indicate cube root.

OpenStudy (firejay5):

is that all for #11

OpenStudy (aum):

yes.

OpenStudy (aum):

For #12, you can factor out -1 out of the squaring which will make it +1 so it becomes (x+2)^2 - 3. But it is up to you if you want to simplify. It all depends on what your teacher is expecting. Both answers are correct.

OpenStudy (aum):

#13 should be \(\large -\sqrt{x+2}\)

OpenStudy (aum):

#14) Parent f(x) = x^3 vertical stretch by a factor of 3: 3f(x) = 3x^3 left by 4: 3(x+4)^3 down 6: 3(x + 4)^3 - 6

OpenStudy (aum):

#15 is correct.

OpenStudy (aum):

Is 16 reflected over x or the y axis?

OpenStudy (firejay5):

x-axis

OpenStudy (aum):

#16) \(\Large -\frac 13\sqrt[3]{x+1}\)

OpenStudy (firejay5):

- 5 my bad

OpenStudy (aum):

#16 \(\Large -\frac 13\sqrt[3]{x+1} - 5 \)

OpenStudy (aum):

So what is the answer to my sample question earlier?

OpenStudy (aum):

f(x) = (5x)^3. Shift the function to the right by 2 units. What will be the transformed function?

OpenStudy (firejay5):

17.) f(x) = - (4x - 24)^3 + 2

OpenStudy (aum):

yes, 17 is correct. How about the question above?

OpenStudy (aum):

To shift a function to the right by 2 units, simply replace f(x) with f(x-2). Here f(x) = (5x)^3 f(x-2) = { 5(x-2) }^3 = (5x - 10)^3 and NOT (5x)^3 - 2.

OpenStudy (aum):

gtg.

OpenStudy (firejay5):

thank you for the help, so are all of my answers checked and okayed

OpenStudy (aum):

As far as I can tell they all seem okay except for a few corrections here and there. But a double check is always recommended to catch any silly mistakes.

OpenStudy (aum):

To shift a function to the right by 2 units, simply replace f(x) with f(x-2). Here f(x) = (5x)^3 f(x-2) = { 5(x-2) }^3 = (5x - 10)^3 and NOT (5x)^3 - 2 and NOT (5x - 2)^3.

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