How to find x for this equation : 3x-3(x-1)=3

slega [8]

Answer:

The correct answer, again, is A; Z = -0.6

7 0

2 years ago

A pan of warm water (46∘ Celsius) was put in a refrigerator. After 15 minutes, the water's temperature was 27∘ C; 15 minutes aft

Cloud [144]

Answer:

The refrigerator was at around 13 ∘C

Step-by-step explanation:

Newton's Law of Cooling:

The rate of change of a body temperature (amount of heat loss/time of loss) is directly proportional to the difference between its own temperature and the surroundings.

$\frac{T(t2)-T(t1)}{t2-t1} = -h (T(t2) - Tenv)$

T ⇒ temperature

t ⇒ time

Tenv ⇒refrigerator temperature

$\frac{T(t2)-T(t1)}{t2-t1}$ ⇒ rate of change of he temperature

-h ⇒ constant of proportionality (negative because the temperature is decreasing inside the refrigerator)

We have 3 points:

time (minutes) - Temperature (∘ C)

0 (when the pan was put in the refrigerator) - 46

15 (after 15 minutes) - 27

30 (15 minutes after the first 15 minutes) - 19

$\frac{27 - 46}{15 - 0}$ = -h (27 - Tenv)

$\frac{19 - 27}{15 - 0}$ = -h (19 - Tenv)

Now we have a system of two equations and two variables

$\frac{-19}{15} = -h (27 - Tenv)\\ \frac{19}{15} = h (27 - Tenv)\\ \frac{19}{15(27 - Tenv)} = h$

$\frac{19 - 27}{15 - 0} = -h (19 - Tenv)\\\frac{-8}{15} = -h (19 - Tenv)\\\frac{8}{15} = h (19 - Tenv)\\\frac{8}{15} = \frac{19}{15(27 - Tenv)} (19 - Tenv)\\8(27 - Tenv) = 19 (19 - Tenv)\\216 - 8 Tenv = 361 - 19 Tenv\\19 Tenv - 8 Tenv = 361 - 216\\11 Tenv = 145 \\Tenv = 145/ 11\\Tenv = 13. 18$

The refrigerator was at around 13 ∘C

6 0

2 years ago

On section AB, whose length is 192 cm, take the point C so that AC: CB = 1: 3. The point D is taken on the AC section so that CD

jasenka [17]

Answer:

112 cm

Step-by-step explanation:

Given:

AB = 192 cm
AC : CB = 1 : 3
CD = BC/12
The distance between midpoints of AD and CB = x

Find the length of AC and CB:

AC + CB = AB
AC + 3AC = 192
4AC = 192
AC = 192/4
AC = 48 cm

Find CB:

CB = 3AC = 3*48 = 144 cm

Find the length of CD:

CD = BC/12 = 144/12 = 12 cm

Find the length of AD:

AD = AC - CD = 48 - 12 = 36 cm

Find the midpoint of AD:

m(AD) = 36/2 = 18 cm

Find the midpoint of CB:

m(CB) = AC + 1/2CB = 48 + 144/2 = 48 + 82 = 130 cm

Find the distance between the midpoints:

x = 130 - 18 = 112 cm

4 0

2 years ago

UHHH HELP OMG WHAT IS THIS I WASNT PAYING ATTENTION SORRY 26 POINTS DO NOT GIVE ME AN ANSWER IF U DONT KNOW HELP i know its easy

Karolina [17]

Answer:

m=2/3, b=12

Step-by-step explanation:

When you see an equation in this format, it's called slope-intercept form (y=mx+b, with m being slope and b being y-intercept). So in this case, by looking at our formula, we can tell right away that our slope, or m, is 2/3 and our y-intercept, or b, is 12. HTH :)

3 0

2 years ago

A shop sells DVDs and CDs.

Vsevolod [243]

Answer:

Step-by-step explanation:

Lets Price of a DVD is fixed i.e. 15

and One CD price is 5 (Not fixed)

In First situation

2 DVDs and 1 CD cost = 35 as given

2 x 15 + 5 = 35

Lets one CD price is 7.5

In Second situation

2 x 15 + 2 x 7.5 = 45

Its mean CD price may be between 5 to 7.5

In asked scenario, Martin has 50

1 DVD and 3 CDs?

1 x 15 + 3 x 7.5 = 37.5

37.5 is lesser than 50

Hence Martin has enough to buy 1 DVD and 3 CDs.

3 0

2 years ago