# Tuesday 3/24

Good Morning!!  Today the sun is shining and I hope you make it out for a walk or just some fresh air 🙂  Today is test day for 6th and 7th and 7.5 gp for Algebra. Tomorrow is a day off from lessons!!  So if you are behind and need a catch up day..do that today then take the test or move on to 7.5 tomorrow.   Some students have been working hard but are a little bit behind and that’s ok!! This is new to all of us and you are doing a great job!!  Those of you that are on track or even ahead, spend 10 minutes on Khan Academy. You can look up a course and try your hand at learning something new or practicing something that gives you trouble.  If you can’t find anything let me know and I have an idea or 2 😉

7th grade: Take test 15A. This is an open book test and you may use a calculator on all problems!! 🙂

8th grade: Read 7.5 and do guided practice questions. Exponential decay  – when a quantity decays exponentially, it decreases by the same percent over equal time periods. This is the opposite of exponential growth which we covered in 7.4.  Let’s look at these more closely. For exponential decay, each time the value of x increases by 1, the value of ya” is multiplied by a constant amount b, where 0<b<1. This gives us the same function,

y=ab^2 (^means superscript..sorry this platform won’t accept the math keyboard from google and is very limited with text)

as exponential growth, except in exponential growth, b>1. The exponential growth model is

y=a(1 + r)^t

now let’s look at the exponential decay model which is

y=a(1 – r)^t

They are opposites 🙂 Now, what do all these variables mean?  We start with a is our initial value, r is the decay rate, 1-r is the decay factor and t is the time period. I hope that helps! Let me know if you have any questions 🙂

Have a great day!

Mrs. McCarthy 