What is the circumference of a ceiling fan

Tamara rewrote the expression 0.2(4+1.4y - 2.1). Her steps are shown.

grin007 [14]

Answer:

Her first mistake was in Step 2. She added 0.2 to each term instead of multiplying by 0.2.

Step-by-step explanation:

CORRECT WAY:

0.2(4+1.4y - 2.1)

0.8 + 0.28y - 0.42

0.8 - 0.42 + 0.28y

0.38 + 0.28y

WHAT TAMARA DID:

0.2(4+1.4y - 2.1)

How she got 4.2: 0.2 + 4 = 4.2

How she got 1.6y: 0.2 + 1.4y = 1.6y

How she got -1.9: 0.2 + -2.1 = -1.9

WHAT SHE DID HERE IS WRONG. REMEMBER WHEN IT IS __( ______) IT MEANS THAT YOU NEED TO MULTIPLE NUMBER OUTSIDE THE PARATNESS TO EVERY NUMBER THAT IS INSIDE THE PARATNESS.

4 0

2 years ago

Do the ratios 30/24 and 20/16 form a proportion?

BartSMP [9]

Answer:

Yes.

Step-by-step explanation:

Reduce both fractions.

30/24 = 5/4
20/16= 5/4

6 0

3 years ago

Write AB−⇀− with A(−7,5) and B(−3,−7) in component form.

Sladkaya [172]

Answer:

ANSWER: (4, -12)

Step-by-step explanation:

Lol

8 0

2 years ago

One thousand and twenty students participated in the school math contest.

Tema [17]

Answer:

sample 1: 75

sample 2: 86

Step-by-step explanation:

6 0

2 years ago

A colony of bacteria is growing at a rate of 0.2 times its mass. Here time is measured in hours and mass in grams. The mass of t

11Alexandr11 [23.1K]

Answer:

Question 1: $dm/dt=0.2m$

Question 2: $m=Ae^{(0.2t)}$

Question 3: $m=10e^{(0.2t)}$

Question 4: $m=10g$

Explanation:

Question 1: Write down the differential equation the mass of the bacteria, m, satisfies: m′= .2m

a) By definition: $m'=dm/dt$

b) Given: $rate=0.2m$

c) By substitution: $dm/dt=0.2m$

Question 2: Find the general solution of this equation. Use A as a constant of integration.

a) Separate variables

$dm/m=0.2dt$

b) Integrate

$\int dm/m=\int 0.2dt$

$ln(m)=0.2t+C$

c) Antilogarithm

$m=e^{0.2t+C}$

$m=e^{0.2t}\cdot e^C$

$e^C=A\\\\m=Ae^{(0.2t)}$

Question 3. Which particular solution matches the additional information?

Use the measured rate of 4 grams per hour after 3 hours

$t=3hours,dm/dt=4g/h$

First, find the mass at t = 3 hours

$dm/dt=0.2m\\\\4=0.2m\\\\m=4/0.2\\\\m=20g$

Now substitute in the general solution of the differential equation, to find A:

$m=Ae^{(0.2t)}\\\\20=Ae^{(0.2\times 3)}\\\\A=20/e^{(0.6)}\\\\A=10.976$

Round A to 1 significant figure:

A = 10.

Particular solution:

$m=10e^{(0.2t)}$

Question 4. What was the mass of the bacteria at time =0?

Substitute t = 0 in the equation of the particular solution:

$m=10e^{0}\\\\m=10g$

3 0

2 years ago