My Math Forum Can you help me answer following mathematical questions?

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 December 22nd, 2018, 06:07 PM #1 Newbie   Joined: Dec 2018 From: Fife WA Posts: 6 Thanks: 0 Can you help me answer following mathematical questions? Let f(w) = 2w^3 - 5. What is f(4)? Let f(w) = 2w^3 - 5. Let z = 2. What is f(z)? Let g(x) = cos(x/2) - 3x. Let f(x) = 2x + 5. What is g(f(x))? Let f(x) = tan(x) - 2/x. Let g(x) = x^2 + 8. What is f(x)*g(y)? What is the derivative of x^2 - x + 3 at the point x = 5? What is the value of x where x^2 - x + 3 is a minimum? In Python, what is returned when evaluating [n for n in range(10) if n % 2]? In Python, what kind of error is returned by the following code? (e.g. NameError, ValueError, IOError, etc.) def my_func(n1, n2): return n1 + n2 my_func(1, 2, 3) What is returned by datetime(1970, 1, 1).strftime('%Y-%d-%B') in Python?
December 22nd, 2018, 06:13 PM   #2
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Quote:
 Originally Posted by Hellov Let f(w) = 2w^3 - 5. What is f(4)?

December 22nd, 2018, 06:40 PM   #3
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Quote:
 Originally Posted by maschke what are your thoughts? Do you understand what they're asking?
1019

December 22nd, 2018, 07:40 PM   #4
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 Originally Posted by Hellov 1019
That's not what I get. I asked if you understand exactly what they're asking. Perhaps you are not understanding the notation. Do you understand what they mean by f(4)?

December 22nd, 2018, 07:53 PM   #5
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 Originally Posted by Maschke That's not what I get. I asked if you understand exactly what they're asking. Perhaps you are not understanding the notation. Do you understand what they mean by f(4)?
Oh, I think I made a mistake...

I used 8 instead of 4.

But I was supposed to do
2 x 4x4x4 - 5 = 123 correct?

Last edited by skipjack; December 23rd, 2018 at 08:52 AM.

December 22nd, 2018, 11:11 PM   #6
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Quote:
 Originally Posted by Hellov Oh, I think I made a mistake... I used 8 instead of 4. But I was supposed to do 2 x 4x4x4 - 5 = 123 correct?
Yes, good. Can you do the second one? This is a pretty mixed bag of questions. Which one(s) are you having trouble with?

Last edited by skipjack; December 23rd, 2018 at 08:52 AM.

December 22nd, 2018, 11:38 PM   #7
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Quote:
 Originally Posted by Maschke Yes, good. Can you do the second one? This is a pretty mixed bag of questions. Which one(s) are you having trouble with?
I have trouble with all of them...can you just answer them please

December 23rd, 2018, 05:50 AM   #8
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Quote:
 Originally Posted by Hellov I have trouble with all of them...can you just answer them please
No. You are a troll.

-Dan

December 23rd, 2018, 08:50 AM   #9
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Quote:
 Originally Posted by Hellov I was supposed to do 2 x 4x4x4 - 5 = 123 correct?
The next two questions are done similarly.

For z = 2, f(z) = f(2) = 2(2)³ - 5 = 2(8) - 5 = 11.

For f(x) = 2x + 5, g(f(x)) = g(2x + 5) = cos((2x + 5)/2) - 3(2x + 5),
which can be simplified to cos(x + 5/2) - 6x - 15.

In the next question, "*" denotes multiplication.

For f(x) = tan(x) - 2/x and g(x) = x² + 8, f(x)*g(x) = (tan(x) - 2/x)(x² + 8).

The next two questions should have been posted in the calculus forum.

The derivative of x² - x + 3 is 2x - 1. At x = 5, that is 9.

Where x² - x + 3 is a minimum, its derivative is zero, so 2x - 1 = 0.
The required value of x is therefore 1/2.

Your remaining questions, relating to Python, should be posted separately in the Computer Science Forum.

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# let f(w) = 2w^3 - 5. what is f(4)

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