Homework Help Thread--SPLIT

[Mongrel]

We learned this poem with I was in fifth grade. I don't always remember every couplet from the poem, but I've always remembered the parts of speech.
And here's a place that will let you create your own vocabulary test.

[Xaidread]

Thanks for the help, Moongewl! I've got to bookmark that site after I finish making the test.

[stephanie<3]

Does anyone know where I can find something about the ancient Romans trying to rule territory from Spain to Asia Minor? My book is no help. Thank you a bunch to anyone who can help.

[Eidolon]

This. is. driving. me. crazy.

I have literally spent a couple hours on this, trying it different ways, but not getting the correct answer. Help.

"If a ball is thrown into the air with a velocity of 37 ft/s, its height (in feet) after t seconds is given by y = 37t - 16t2. Find the velocity when t = 1."

I'm in calculus and we're working on limits and derivatives -- so I should take f ' (1), right? But when I do that and solve it through, I end up with 21, which according to WebAssign is not the correct answer.

This isn't a case of not knowing HOW to do it...it's that I don't know WHAT to do with what I know

Any help is *greatly* appreciated.

[Siniri]

This. is. driving. me. crazy.

I have literally spent a couple hours on this, trying it different ways, but not getting the correct answer. Help.

"If a ball is thrown into the air with a velocity of 37 ft/s, its height (in feet) after t seconds is given by y = 37t - 16t2. Find the velocity when t = 1."

I'm in calculus and we're working on limits and derivatives -- so I should take f ' (1), right? But when I do that and solve it through, I end up with 21, which according to WebAssign is not the correct answer.

This isn't a case of not knowing HOW to do it...it's that I don't know WHAT to do with what I know

Any help is *greatly* appreciated.

What is the formula you got for f'(1)? I think I know what you did wrong -- look carefully at the second part of the equation. (I don't want to give it away, but I do want to help.)

[Eidolon]

Okay...I figured it out, after beating my head against a wall some more -_-

Still not sure what I did WRONG the first time, but I know I did something differently the second time! The key to this seems to be working agonizingly slow...there's just so many places for you to accidentally mess up a sign or a variable or something.

Thank you

[shapu]

Well, the answer is 5, right?

When you take the derivative of an equation, you step the exponents of the variables down by one power, and then multiply the OLD power by the coefficient.

You were correct in recalling that the equation for height (distance) is the derivative of the equation for velocity.

So the finding the derivative would go like this (note I use a carat, ^, to identify exponents):

y = 37t - 16t^2

Is the same as

y = 37t^1 - 16t^2

So, we step down the exponents:
y' = 1*37t^(1-1) - 2*16t^(2-1)

Which gives us

y' = 1*37t^0 - 2*16t^1

t^0 is 1 (any number to the zero power is 1, you'll recall). Similarly, t^1 is obviously just t.

y' = 1*37*1 - 2*16t

Simplify:

y' = 37 - 32t

Input t = 1, and get 5.

(side note: this is easily checked by remembering that acceleration downward due to gravity is 32 f/s. If the initial upward velocity is 37, and we look at t=1, then 37-32 = 5).

[Xaidread]

Apparently, I need to explain how to simplify this problem:
14x + 8 - 20x / 5 + 2(x - 1)

Using my calculator, I've gotten the answer 6 but I don't know how I do the math so I can't get to the explaining. My calculator also says that anything with x is 0.

[Byakuya San]

Apparently, I need to explain how to simplify this problem:
14x + 8 - 20x / 5 + 2(x - 1)

Using my calculator, I've gotten the answer 6 but I don't know how I do the math so I can't get to the explaining. My calculator also says that anything with x is 0.

Hmm...I can't tell how much you know about simplifying, so I'll just give you the full lecture.

Since that problem has a variable (x), you can't simplify it down to just a number: the simplified form will have to have x in it, since you don't know what x equals (don't go with your calculator on these kinds of problems). You have to combine the x terms, then do the rest of the math. Make sure you get 4x out of 20x /5. Also, you'll have to distribute for 2(x-1)--which gives you 2x-2. You should end up with something like -6x + 8 - 4x + 2x +2, which is much easier to simplify than the original equation.

If you need an easier example, take a look at this problem:
7x + 5(x+4)
First, distribute the 5 to get 5x + 20. Then add the 5x and 7x. Your final answer would be 12x + 20. This IS simplified even though it isn't just one number.

I hope I wasn't just restating what you already knew there.

[Pudding]

Split! Continue helping here: viewtopic.php?f=20&t=37519