Melody

Thankyou but you need to give examples of how this could be used :)

What an excellent answer. :)

Thanks answering guest. :))

If the daily exponential decay is 3%, how many days will it take for the amount to be reduced to 4% of the original?

Hi Saintcyr :)

let the initial amount be X, let n be the number of days that have past.

end of day n           A=X*0.97^n  

When will       A=0.04X

0.04X=X*0.97^n

0.04 = 0.96^n

log 0.04 = log 0.97^n

log 0.04 = nlog 0.97

n=log0.04/log0.97

n=105.7

so after 105.7 days there will be 4% remaining

so after 106 days there will be less than 4% remaining.

5 cents in 1964. It was 49 cents in 2014.  Using your linear model, find the year in which postage was 37 cents. Round to a whole year.

Let 1964=year0      so  2014=year  50

y=m*x +5

49=m*50+5

44=50m

m=44/50 = 88/100 = 0.88

so

y=0.88x+5

Find x when y=37

37=0.88x+5

32=0.88x

x=32/0.88 = 36   to the nearest whole.

1964+36 = 2000

So if the linear model is accurate then the price was 37c in the year 2000.

Let g(x) be reflected of f(x)=x^2+5 in the axis. What is the function rule for g(x)?

f(x) is a concave up parabola, the vertex is (0,5) and the axis of symmetry is the x axis   (x=0)

If it is reflected in  the y axis it will stay the same so   g(x)=x^2+5

If it is reflected in the x axis    (about y=0)   then it will still have the y axis as the axis of symmetry but it will be concave down and the vertex will be (0,-5)

so   g(x)= -x^2 - 5

Which axis is it reflected in?

1. When the Gupta's granddaughter was born recently, they opened a saving account in her name with a 
deposit of $1000. In addition, they plan to add $100 to the account every quarter up to and including her 
thirteenth birthday. If the account earns interest at 4% compounded quarterly, how large will her account be 
when she turns 13?  

The first $1000 is a straight compound interest questions

FV = 1000*1.01^52

FV= $1677.68

The ongoing $100 deposits is the future value of an ordinary annuity. 

i=0.04/4=0.01     n=13*4=52 months  C=100

\(FV=100*\frac{1.01^{52}-1}{0.01}\\\\ FV=6776.89\)

So altogether she will have   1677.68+6776.89 = $8454.57   on her 13th birthday.   :)

Guest answerer, you got the same answer as I did but without working your answer had no teaching value and no one who understood could check your answer unless they did the whole thing themselves.  But good work, you did get it correct.  If you used a site to get the answer you should have shared that with us as well :))

19-(-5/2 x)=34

multiply both sides by 2

38-(-5x)=68

38+5x=68

5x=30

x=6

9/8 x -2

I appreciate your good manners :)

\(\frac{9}{8}\times \frac{-2}{1}\\\\ =\frac{9}{\not{8}^4}\times\frac{ -\not{2}^1}{1}\\\\ =\frac{9*-1}{4*1}\\\\ =\frac{-9}{4}\\\\ =-2\frac{1}{4}\)

There is no pic so how would anyone know.
You need to be a member to post pics.