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# Omg plz help with this question

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Omg plz help with this question

also this question is a bit diffucult- will i need to plug in some number in for x to figure out which answer choice is correct?

Mar 22, 2019

### 8+0 Answers

#1
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First equation gives the input  RATE.....second equation gives the output RATE

first equation - second equation = net input rate    (like how much is filling the tub)

(3)    will tell you the NET RATE of tank filling at 3 hr

3(3^2)+2     -   (4(3)-1 )=

29 - 11 = 18     After 3 hours THE FILLING RATE is 18 gallons/hr

Mar 22, 2019
edited by ElectricPavlov  Mar 22, 2019
edited by ElectricPavlov  Mar 22, 2019
edited by ElectricPavlov  Mar 22, 2019
#2
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When debt = 0   f(x) = 0

0 = -4x^2+10x+60       Solve for x

I used quadratic formula

$$x = {-b \pm \sqrt{b^2-4ac} \over 2a}$$      with a = -4  b = 10  c = 60   to find x = -2.82   and  5.32    (throw out the negative)   5.3 years

Mar 22, 2019
#3
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Thanks, ElectricPavlov! Is CPhill still typing an answer?

Guest Mar 22, 2019
#4
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I dunno.....I think he may have gone for a beer !

ElectricPavlov  Mar 22, 2019
#5
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Ok thx, & you said the answer for the second question is 5.3?

Guest Mar 22, 2019
edited by Guest  Mar 22, 2019
edited by Guest  Mar 22, 2019
edited by Guest  Mar 22, 2019
#6
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Sorry...I misread the question and edited my answer...... third choice

ElectricPavlov  Mar 22, 2019
#7
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Yes.....................5.3 years

ElectricPavlov  Mar 22, 2019
#8
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( i - d)(3)   is the rate at which the volume of liquid is changhing at 3 hrs....to find this we have

[ 3(3)^2 + 2 ] - [ 4(3) - 1 ]  =

[ 27 + 2 ] - [11[  =

29  - 11  =

18 gal per hour    (third answer )

Next one

We want to find when the debt = 0   .....so.....

-4x^2 + 10x + 60  = 0        divide through by - 2

2x ^2 - 5x - 30  =  0

The graph here shows that the company will get out of debt after about 5.3 years

https://www.desmos.com/calculator/rtundu47as

Mar 23, 2019