Question

Please check my work in the comments



During the period 1985-2012, the projected enrollment B (in thousands of students) in public schools and the projected enrollment R in (in thousands of students) in private schools can be modeled by
B = -18.53t^2 + 975.8t + 48,140
and
R = 80.8t + 8,049

where t is the number of years.

A: Write an equation that models the difference in the projected enrollments for public schools and private schools as a function of the number of years since 1985

B: Find the difference in projected enrollments for public schools and private schools in 2005.

Answer 1

A: You need to find B - R. Subtract as follows:
\[\large B-R=-18.53t^{2}+975.8t+48,140-(80.8t+8,049)\]

Answer 2

@bookish610 Can you do the subtraction?

Answer 3

yep doing it now. (on paper)

Answer 4

would it be this?
\[B-R = -99.33t + 955.8t + 40.091\]

Answer 5

Not really. Perhaps the subtraction will be clearer if like terms are grouped, as follows:
\[\large B-R=-18.53t^{2}+(975.8t-80.8t)+(48,140-8,049)=?\]

Answer 6

Note that the term -18.53t^2 will be unchanged in the result of subtraction.

Answer 7

\[B-R = -18.53t^{2} + 895t + 40,091\] ?

Answer 8

Yes, that is correct.
B: Now you need to find the number of years between 2005 and 1985, and then substitute that number for t in your equation for A:

Answer 9

\[\large B-R(at\ 2005)=(-18.53\times20^{2})+(895\times20)+40,091=?\]

Answer 10

\[B-R = 50,579\]
?

Answer 11

@kropot72
Did I get it right?

Answer 12

Can someone please tell me if I got this right?

Answer 13

please guys

Answer 14

I AM A STRESSED OUT HIGH SCHOOL STUDENT AND I DO NOT NEED YOUR SHENANIGANS

Answer 15

I need someones help

Answer 16

x'D im sorry i just cant help but find that funny XD

Answer 17

medal for medal?anyone

Answer 18

well i'm glad someone is finding humor in my PAIN

Answer 19

HAHAHAHAH

Answer 20

first t=20 so first plug in 20 for all the t's because 2005-195 is 20 years

Answer 21

1985

Answer 22

Does that make sense?

Answer 23

Yeah. I think I did some of this earlier. Did you see the equation and what I think is the correct answer?

Answer 24

Just a second gotta grab my calculator :)

Answer 25

ok

Answer 26

That is not what I got

Answer 27

First let's separate everything up so you have the equation -18.53t^2+975.8t+48140 so first let's plug in our 20 for the t's, and I like to put the parenthesis around the t's or the number your plugging in

Answer 28

So -18.53(20)^2+975.8(20)+48140 what do you get there?

Answer 29

wait
is that last part right? isn't it
-18.53(20)^2+975.8(20)+40091 ?

Answer 30

It's 48140

Answer 31

At least that was what was typed

Answer 32

It that what it says into your book or wherever this problem is coming from?

Answer 33

it's up farther where somebody was helping me figure out what the equation for part A was

Answer 34

Oh I see you guys reduced it okay you don't have to do the long process I was going to do but either way works too :) or should work

Answer 35

so if I use the equation from earlier it comes out as
52,195

Answer 36

Yes that is right, I must have punched something In wrong my bad

Answer 37

You could also you the original equation and go (-18.53(20)^2975.8(20)+48140)-(80.8(20)+8049) doesn't matter which way you do it :) you get the same answer

Answer 38

Oops I messed up with the first part (-18.53(20)^2+975.8(20)+48140) but good job :)

Answer 39

Do you have any other questions

Answer 40

yeah. three more two part word problems and one semi regular problem

Answer 41

Okay :) and sorry I didn't help you on Friday I got really busy

Answer 42

Yes, your answer 50,579 is correct.