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3 years ago

11

Assign two variables for each problem, and write the equations. Do not solve.

2 answers:

hichkok12 [17]3 years ago

5 0

1. x represents one battery, y represents the other battery x+y=6.5 x-y=2.5 2. x represents the number of small drinks sold, y represents the number of other size drinks sold x+y=230 x+1.5y=285

Luba_88 [7]3 years ago

5 0

A = first battery type
b = second battery type

a + b = 6.5 V
a = ( 6.5 V ) - b

b - a = 2.5 V

b - (6.5 - b) = 2.5
2b - 6.5 = 2.5
2b = 9.0
b = 4.5 V
a = 6.5 - 4.5
a = 2.0 V

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Which problem can we solve with 27 : 3?

N76 [4]

Answer:

La Tasha has 27 rabbit stickers. She splits the stickers

evenly among 3 pieces of paper. How many stickers

did La Tasha put on each piece of paper?

Step-by-step explanation:

6 0

3 years ago

Initially 100 milligrams of a radioactive substance was present. After 6 hours the mass had decreased by 3%. If the rate of deca

Hitman42 [59]

Answer:

The half-life of the radioactive substance is 135.9 hours.

Step-by-step explanation:

The rate of decay is proportional to the amount of the substance present at time t

This means that the amount of the substance can be modeled by the following differential equation:

$\frac{dQ}{dt} = -rt$

Which has the following solution:

$Q(t) = Q(0)e^{-rt}$

In which Q(t) is the amount after t hours, Q(0) is the initial amount and r is the decay rate.

After 6 hours the mass had decreased by 3%.

This means that $Q(6) = (1-0.03)Q(0) = 0.97Q(0)$ . We use this to find r.

$Q(t) = Q(0)e^{-rt}$

$0.97Q(0) = Q(0)e^{-6r}$

$e^{-6r} = 0.97$

$\ln{e^{-6r}} = \ln{0.97}$

$-6r = \ln{0.97}$

$r = -\frac{\ln{0.97}}{6}$

$r = 0.0051$

So

$Q(t) = Q(0)e^{-0.0051t}$

Determine the half-life of the radioactive substance.

This is t for which Q(t) = 0.5Q(0). So

$Q(t) = Q(0)e^{-0.0051t}$

$0.5Q(0) = Q(0)e^{-0.0051t}$

$e^{-0.0051t} = 0.5$

$\ln{e^{-0.0051t}} = \ln{0.5}$

$-0.0051t = \ln{0.5}$

$t = -\frac{\ln{0.5}}{0.0051}$

$t = 135.9$

The half-life of the radioactive substance is 135.9 hours.

6 0

3 years ago

1. what is 60% of 50? 20 or 30?<br> 2. 50% of 40? 20 or 30<br> 3. 12% of 50? 20 or 30

34kurt

Answer:

1: 30

2: 20

3: 6

Step-by-step explanation:

1: .60 x 50 = 30

2: .50 x 40 = 20

3. .12 x 50 = 6

Idk why your two answers for 3 are 20 and 30 but neither of those are the answer

5 0

3 years ago

Read 2 more answers

Simplify for a = 3, b = -4 and c = -1.<br><br> 9−a(c+5)

Otrada [13]

9 - a (c + 5)
9 - 3 * 4
9 - 12
solution is -3

5 0

3 years ago

Read 2 more answers

3x-5y=15 find y when x=1

Lapatulllka [165]

Answer:

-2.4

Step-by-step explanation:

3(1)-5y=15

3-5y=15

-3 -3

-5y=12

÷-5 ÷-5

y=-2.4

I'm sorry if it's incorrect! I tried!

7 0

3 years ago