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3 years ago

Please help me this is from khan academy :(((

Mathematics

1 answer:

Dmitrij [34]3 years ago

6 0

Answer:

y=1.4x+6.8

Step-by-step explanation:

(-2;4) (-7;-3)

4=-2k+b

-3=-7k+b

7=5k

k=1.4

-2.8+b=4

b=6.8

I already know k and b so I can write an equation.

y=1.4x+6.8

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A lake polluted by bacteria is treated with an antibacterial chemical. Aftertdays, thenumber N of bacteria per milliliter of wat

jeyben [28]

Answer:

N(1)=50 is a minimum

N(15)=4391.7 is a maximum

Step-by-step explanation:

Extrema values of functions

If the first and second derivative of a function f exists, then f'(a)=0 will produce values for a called critical points. If a is a critical point and f''(a) is negative, then x=a is a local maximum, if f''(a) is positive, then x=a is a local minimum.

We are given a function (corrected)

$N(t) = 20(t^2-lnt^2)+ 30$

$N(t) = 20(t^2-2lnt)+ 30$

(a)

First, we take its derivative

$N'(t) = 20(2t-\frac{2}{t})$

Solve N'(t)=0

$20(2t-\frac{2}{t})=0$

Simplifying

$2t^2-2=0$

Solving for t

$t=1\ ,t=-1$

Only t=1 belongs to the valid interval $1\leqslant t\leqslant 15$

Taking the second derivative

$N''(t) = 20(2+\frac{2}{t^2})$

Which is always positive, so t=1 is a minimum

(b)

$N(1)=20(1^2-2ln1)+ 30$

N(1)=50 is a minimum

(c) Since no local maximum can be found, we test for the endpoints. t=1 was already determined as a minimum, we take t=15

(d)

$N(15)=20(15^2-2ln15)+ 30$

N(15)=4391.7 is a maximum

7 0

3 years ago

Help!!! I just need Help on number 6 please!!!!!!!! ASAP!!!

PtichkaEL [24]

Answer:

$3$

Step-by-step explanation:

$\sqrt{12} =3.46$ (2 decimal places)

If you want to arrange the tiles into a square, you will need 3.46 in each row/column.

This is physically impossible, hence you round it down to 3.

(If you round it up, you won't have enough tiles since $4*4=16$ )

Thus, the square area will be $3*3=9$

Tiles left: $12-9=3$

6 0

3 years ago

Divide the complex numbers

Otrada [13]

Answer:

1/4 - 1/3i

Step-by-step explanation:

(4+3i)(-i) / 12i(-i)

= 3 - 4i / 12

3 0

3 years ago

FIND THE DEGREE MEASURE OF ANGLE DPR.

SVETLANKA909090 [29]

$\widehat{DPR}=\frac{1}{2}(\stackrel\frown{ET}-\stackrel\frown{DR}) = \frac{1}{2} (118 - 26) = \frac{92}{2} = 46°$

4 0

3 years ago

a scientist from chile has transported volcanic ash samples to be tested in his lab if the scientist has 3540 grams of volcanic

Digiron [165]

3,540 grams of ash
If its density is 2.75 g/cc and
density = mass / volume then its volume is

volume = mass / density
volume = 3,540 g / 2.75 g / cc
volume = 1287.272727 cc
So, rounded it is 1,287.3 cubic centimeters but to keep the same number of significant figures, the volume is
volume = 1,287 cc

7 0

3 years ago