CPhill

csc = 1/sin      

sec =  1/cos

cot = 1/tan

Hayley.......

Do you have a Facebook account????....If so......you should be able to use Facebook email to set up an account on here.......

Knowing this, Hayley.....can you find the vertex of

y - 8 =  (x + 3)^2          ????

y + 9  =  (x - 4)^2

You have the x coordinate correct

Put it in this form, Hayley

y  = (x - h)^2  +  k

So we have.......  [subtracting 9 from both sides]

y = (x - 4)^ - 9

In this form.....the vertex can be read thusly, as  ....      (4 , -9)

In other words......the x coordinate of the vertex is the x value that makes x - 4  = 0  [this is 4[......   and the y coordinate  is just the last term and its associated sign.......

Let x be the number of $5 bills and y be the number of $10 bills

And x + y  = 25    (1)

And value of a five dollar bill * x  +  value of a ten dollar bill * y  = total amount   ......in other words.....

5x + 10y  = 230   (2)

Rearranging (1), we have that   y = 25 - x      and putting this into (2), we have

5x + 10(25 - x)  = 230    simplify

5x + 250 - 10x   = 230

-5x + 250  = 230       subtract 250 from both sides

-5x  = -20            divide both sides by -5

x = 4     this is the number of $5 bills she has

And  y = 25 - x   =    25 - 4   =   21     .....and this is the number of $10 bills she has

Here you go, Hayley..........http://www.purplemath.com/modules/parabola.htm

This is pretty detailed, so take it slowly.......!!!!!!

We can use this formula:

A = A₀ * 2 ^-t/h      where A  is the amount left after t hours   A0 is the original amount    and h is the half-life in hrs.  ....so we have....

A = 18 * 2 ^-60/15    

A = 18 * 2^-4       

A = 18/ 16   =   9/8  grams 

The % error  is given by :

abs [ True Value - Estimated Value] /  [ True Value]  =

abs [ 499.7 - 500]  / 499.7    =  about .06%

-7s = 938        divide both sides by -7

s = 938 / -7   =   - 134

No problem, Shades.....glad it helped.....