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2 years ago

10

What is the value of the expression below? -5 * (3^2 - 2) + (7 * 5 + 7) / 6

1 answer:

iVinArrow [24]2 years ago

3 0

Answer:

-5 * (3^2 - 2) + (7 * 5 + 7) / 6=-28

Hope This Helps!!!

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A man paid $42.30 for gasoline in may, $38.60 in June, and $43 in July. What was the average monthly cost for gasoline?

jeyben [28]

The average is $41.30

3 0

3 years ago

Zach wants to build a slanted skateboard ramp. He knows he wants the ramp to form a 15 degrees angle with the ground and be 4 fe

Fynjy0 [20]

Answer: The ramp would be 15.5 feet long.

Step-by-step explanation: Please refer to the attached diagram for details.

Angle C shows the angle to be formed by the ramp from the ground, which is 15 degrees. Also, from the ground, it’s going to be four feet tall, which is line AB. The top of the ramp is point A, which makes line AC the entire length of the ramp. Since we have a reference angle (angle C) and two sides, the opposite and the hypotenuse, we shall apply the trigonometric ratio.

SinC = opposite/hypotenuse

Sin 15 = 4/b

By cross multiplication we now have

b = 4/Sin15

b = 4/0.2588

b = 15.4599

Approximately b = 15.5

Therefore the length of the ramp would be 15.5 feet

6 0

2 years ago

The volume of Cylinder A is 189 ft and the

andrezito [222]

Answer:

27:8

Step-by-step explanation:

189/56 = 27/8

6 0

2 years ago

What is 5 times (2+8)+(12-6/3)times2

Hatshy [7]

Answer:

5(2+8)+(12-6/3)2

5(10)+(12/1-6/3)2

50+(36/3-6/3)2

50+(30/3)2

50+60/3

50+20

70

Step-by-step explanation:

3 0

2 years ago

Read 2 more answers

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

2 years ago