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Mathematics 13 Online
zarkam21:

Help please

zarkam21:

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Vocaloid:

it says nothing about whether a or b have to be positive/negative/integers/whatever you only know that b is an exponent and that means b is the number that says how many times to multiply a by itself so A+D

zarkam21:

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Vocaloid:

|dw:1517462564775:dw|

Vocaloid:

just start off with the a terms use rule 1 + 2 to simplify (a^2 * a^3)/(a^5)

Vocaloid:

gonna go to sleep tag me again when you're awake

zarkam21:

@Vocaloid I'm back

Vocaloid:

\(\color{#0cbb34}{\text{Originally Posted by}}\) @Vocaloid just start off with the a terms use rule 1 + 2 to simplify (a^2 * a^3)/(a^5) \(\color{#0cbb34}{\text{End of Quote}}\) have you made any progress on this?

zarkam21:

well this simplified would be a^5

Vocaloid:

the numerator becomes a^5 so (a^5)/(a^5) = ?

zarkam21:

1

Vocaloid:

good, now we move on to the b terms b * b^2 = ?

zarkam21:

b^3

Vocaloid:

good, now we move on to the c terms c/(c^2 * c^4) = ?

zarkam21:

1/c^5

Vocaloid:

good so putting everything together --> b^3/c^5 --> your answer

zarkam21:

thank you

zarkam21:

\[\log (\frac{ (x+y)^3(x-y)^2 }{ x^2+y^2 })\]

zarkam21:

is this the right answer for this

zarkam21:

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Vocaloid:

yup good

zarkam21:

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Vocaloid:

it's basically just the reverse of what you just did, separate the components of the log then drop the exponent down as coefficients

Vocaloid:

2log(x+3)... then continue with the rest of the log

zarkam21:

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Vocaloid:

the website is trying to expand the logarithm all the way even though it's probably not needed 2log(x+3) - log(x-2) - 4log(x^2+5) is what they are looking for

zarkam21:

rewrite as an exponential equation \[\ln (x+y)=5\]

Vocaloid:

raise both sides to the power of e

zarkam21:

e^5=x+y

Vocaloid:

good but you might want to re-write that as y = e^5 - x so it looks like an equation of y in terms of x

zarkam21:

rewrite as an logarithmic equation 2^4=(a-b)

Vocaloid:

|dw:1517497396050:dw|

Vocaloid:

y = (a - b), b is the base 2 and x is the exponent 4 re-write in the log form

zarkam21:

log2(a-b)=4

Vocaloid:

good

zarkam21:

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zarkam21:

I'm sorry not this one

zarkam21:

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zarkam21:

a. 5 b. -4 c. -3 d. 0

Vocaloid:

well done

zarkam21:

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zarkam21:

I dont know how to solve this for t

Vocaloid:

divide both sides by 500 first then take the natural log of each side then dividing by 0.06 will isolate t

zarkam21:

4.709

Vocaloid:

check your calculations again let's just take it one step at a time, divide both sides by 500 and lmk what you get

zarkam21:

5=e^0.06t

Vocaloid:

good, now take the natural log of each side

zarkam21:

wait is it 26....?

Vocaloid:

good but it wants 3 decimal places so your answer would be...?

zarkam21:

26.824

Vocaloid:

good, that's it

zarkam21:

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Vocaloid:

since ln(0) is undefined which two choices can you eliminate right off the bat?

zarkam21:

um c

Vocaloid:

what value of x will make ln(x-5) = ln(0)?

zarkam21:

oh a and b

Vocaloid:

good, a and b are out the actual behavior of ln(x-5) show that it increases quickly before crossing (6,0) so D is the best choice

Vocaloid:

for 13 if we plug in x = 0 we get 6, making A and B possible candidates since the exponent is -x it will keep decreasing as x ---> infinity so B

zarkam21:

=)

zarkam21:

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Vocaloid:

14 - what is the common ratio?

zarkam21:

x3

Vocaloid:

good (just 3) so r = 3 a1 = first term = 2 use nth term = a1 * r ^ (n-1) to find the nth term

zarkam21:

2 * 3 ^ (n-1)

Vocaloid:

good try to remember what n stands for

zarkam21:

21

Vocaloid:

good, n = 12 so evaluate 2 * 3 ^ (n-1)

zarkam21:

69735

Vocaloid:

you left off some digits, it's a very big #

zarkam21:

6973568802

Vocaloid:

good

Vocaloid:

for 15 figure out the common ratio by dividing a3/a2

zarkam21:

0.7

Vocaloid:

good, now we need to figure out what a1 is if a1 * r = a2 then what is a1?

zarkam21:

a1 * r = 0.7

zarkam21:

would r be 6?

Vocaloid:

we calculated r earlier

zarkam21:

0.7

zarkam21:

a1 * 0.7= 0.7 a1=1

Vocaloid:

awesome now you have everything you need|dw:1517499714775:dw| evaluate sum

zarkam21:

so sn=1(1-0.7^n/1-0.7)

Vocaloid:

yes, keep going

zarkam21:

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Vocaloid:

remember what n stands for also don't enter sn into the formula, it will treat sn as s*n

Vocaloid:

just enter this part 1(1-0.7^n/1-0.7) and replace n w/ the appropriate value

zarkam21:

n is 0.7?

Vocaloid:

n is the number of terms r is 0.7.

zarkam21:

6?

Vocaloid:

good, now evaluate the expression

zarkam21:

0.74

Vocaloid:

check your calculations again, the answer is much bigger than that

Vocaloid:

(1-0.7^6)/(1-0.7) = ?

zarkam21:

2.94

Vocaloid:

good but let's try to leave as many digits as possible so 2.94117

zarkam21:

okay rewrite using radicals\[(a^\frac{ 3 }{ 4 })^5\]

zarkam21:

i got\[(4 \sqrt{a^3})^5\]

Vocaloid:

yeah, that's right (just make sure the 4 is sitting on the radical sign not out in front) also I"m not sure if they'd want you to multiply that 5 through the exponent but let's go with your answer

zarkam21:

rewrite using radical exponents\[\sqrt[5]{x^2}\]

Vocaloid:

basically it's the reverse of the earlier problem, the exponent becomes the numerator of the fraction-exponent and the radical becomes the denominator

zarkam21:

\[x^\frac{ 2 }{ 5 }\]

Vocaloid:

good

zarkam21:

If you deposit $1,000 into an account that pays 4% interest compounded continuously, how long will it take the account to grow to $2,000?

Vocaloid:

A = Pe^rt solve for t

zarkam21:

A = Pe^rt we are given A, P and r: 2000 = 1000e^0.04t divide both sides by 1000: 2 = e^0.04t take Napierian log of both sides: ln2 = 0.04t divide both sides by 0.04: t = ln2/0.04 ~ 17.33 years or 17years 4 months

zarkam21:

is this right

Vocaloid:

yeah that's good

zarkam21:

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Vocaloid:

we want to know when Q(t) = 0.10Q_0 so plug in 0.10Q_0 for Q(t) and solve for t, you're given everything else and Q_0 should cancel out on both sides

zarkam21:

0.1

Vocaloid:

check your calculations again, it should be much bigger than that 0.10Q_0 = Q_0 * e^(-0.07t) solve for t

zarkam21:

0.10= * e^(-0.07t)

zarkam21:

um what would e be?

Vocaloid:

e is euler's number and always has this value |dw:1517501608878:dw|

Vocaloid:

the software you are using should have e automatically programmed into it, look for an italicized e

zarkam21:

32.89

Vocaloid:

this gives me 38 seconds (since they want it rounded up to the nearest second)

zarkam21:

yeah its probably my mistake in calculations

Vocaloid:

for 21 they're probably looking for "exponential" 22 - "limited" 23 - probably 'carrying capacity"

zarkam21:

Thank you so much

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