Assignment 3 query

course Mth 271

003. `query 3*********************************************

Question: `q0.3.24 (was 0.3.24 simplify z^-3 (3z^4)

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Your solution:

When multiplying variables that have exponents, you add or subtract them, depending on the power associated with the exponent. For this problem, I did the following:

z^-3(3z^4)

(3)(z^-3)(z^4)

(3)(z^(-3+4))

3z

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Given Solution:

`a z^-3 ( 3 z^4) = 3 * z^-3 * z^4 = 3 * z^(4-3) = 3 z. **

Self-critique Rating:

I feel very confident about this problem.

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Question: `q0.3.30 (was 0.3.30 simplify(12 s^2 / (9s) ) ^ 3

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Your solution:

(12s^2/9s)^3

(12s/9)^3

(4s/3)^3

(64s^3/27)

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Given Solution:

`a Starting with

(12 s^2 / (9s) ) ^ 3 we simplify inside parentheses to get

( 4 s / 3) ^ 3, which is equal to

4^3 * s^3 / 3^3 = 64 s^3 / 27

It is possible to expand the cube without first simplifying inside, but the subsequent simplification is a little more messy and error-prone; however done correctly it gives the same result. It's best to simplify inside the parentheses first. **

Self-critique Rating:

I feel very confident about this problem.

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Question: `q0.3.38 (was 0.3.38 simplify ( (3x^2 y^3)^4) ^ (1/3) and (54 x^7) ^ (1/3)

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Your solution:

I don’t understand how to do this. I’ve tried to read over your solution but it’s not making sense to me. I’m going to ask for help from a friend and reattempt this problem at a later time.

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Given Solution:

`a To simplify (54 x^7)^(1/3) you have to find the maximum factor inside the parentheses which a perfect 3d power.

First factor 54 into its prime factors: 54 = 2 * 27 = 2 * 3 * 3 * 3 = 2 * 3^3.

Now we have

(2 * 3^3 * x^7)^(1/3).

3^3 and x^6 are both perfect 3d Powers. So we factor 3^3 * x^6 out of the expression in parentheses to get

( (3^3 * x^6) * 2x ) ^(1/3).

This is equal to

(3^3 * x^6)^(1/3) * (2x)^(1/3).

Simplifying the perfect cube we end up with

3 x^2 ( 2x ) ^ (1/3)

For the second expression:

The largest cube contained in 54 is 3^3 = 27 and the largest cube contained in x^7 is x^6. Thus you factor out what's left, which is 2x.

Factoring 2x out of (54 x^7)^(1/3) gives you 2x ( 27 x^6) so your expression becomes

[ 2x ( 27 x^6) ] ^(1/3) =

(2x)^(1/3) * [ 27 x^6 ] ^(1/3) =

(2x)^(1/3) * [ (27)^(1/3) (x^6)^(1/3) ] =

(2x)^(1/3) * 3 x^2, which in more traditional order is

3 x^2 ( 2x)^(1/3). **

Self-critique Rating:

I don’t know how to do this problem and even after reading your solution, it doesn’t make sense to me. I’m going to get help with it and reattempt it at a later time and submit it separately.

Good.

Remember, however, that you aren't expected to understand the more complex expressions of this form just by reading them. You need to write them out on paper, in standard mathematical form, using the conventions indicated in the Typewriter Notation exercises and the associated files.

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Question: `q0.3.58 (was 0.3.54 factor P(1+r) from expression P(1+r) + P(1+r)^2 + P(1+r)^3 + ...

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Your solution:

I had to do a problem like this for a portfolio turned into the IB program when I was in Tri at Virginia High. To get the answer, you factor out P(1 + r) and get the expression:

P(1 + r)[1 + P(1 + r) + P(1 + r)^2 + P(1 + r)^3 …]

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Given Solution:

`a Few students get this one. If you didn't you've got a lot of company; if you did congratulations.

It's important to understand how this problem illustrates the essence of factoring. It's important also because expressions of this form occur throughout calculus.

Factor out P * (1 + r). Divide each term by P ( 1 + r), and your result is P (1 + r) * your quotient.

Your quotient would be 1 + (1+r) + (1+r)^2 + (1+r)^3 + ... .

The factored form would therefore be P(1+r) [ 1 + (1+r) + (1+r)^2 + (1+r)^3 + ... ]. You can verify that this is identical to the original expression if you multiply it back out.

Analogy with different exponents and only three terms: A x^3 + A x^4 + A x^5 can be divided by A x^2 to give quotient x + x^2 + x^3, so the factored expression is A ( x + x^2 + x^3). **

Self-critique Rating:

I feel very confident about the problem.

"

&#Your work looks good. See my notes. Let me know if you have any questions. &#