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3 years ago

6

Write the following expression without negative exponents and without parentheses. 5x^-2

1 answer:

MissTica3 years ago

5 0

Solution:

5x^-2

5 * x^-2

5 * 1/x^2

5/x^2

Best of Luck!

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160% of 42 is what number?

Mandarinka [93]

Answer:

that would be 67.2

Step-by-step explanation:

I hope this helps!

5 0

3 years ago

Need answer thanks! only answer if you know please!

Vaselesa [24]

Answer:

a) $k \approx 0.0602\,\frac{1}{min}$ ( $k\approx 6.02\,\frac{\%}{min}$ ), b) $k \approx 0.0648\,\frac{1}{min}$ ( $k \approx 6.48\,\frac{\%}{min}$ ), c) $t_{1/2} \approx 60.274\,days$ , d) $t_{1/2}\approx 4.305\,min$ , e) $k \approx 0.3\,\frac{1}{min}$ ( $k\approx 30\,\frac{\%}{min}$ ), f) $k \approx 0.0120\,\frac{1}{min}$ ( $k \approx 1.20\,\frac{\%}{min}$ ), g) $k \approx 2.876\times 10^{-5}\,\frac{1}{yr}$ ( $k \approx 2.876\times 10^{-3}\,\frac{\%}{yr}$ )

Step-by-step explanation:

All radioactive isotopes decay exponentially, the mass of the isotope as a function of time ( $m(t)$ ), measured in grams, is defined by:

$m(t) = m_{o}\cdot e^{-k\cdot t}$ (1)

Where:

$m_{o}$ - Initial mass of the isotope, measured in grams.

$k$ - Decay rate, measured in $\frac{1}{min}$ or $\frac{1}{day}$ or $\frac{1}{yr}$ .

$t$ - Time, measured in minutes, days or years.

We define the decay rate in terms of half-life by using the following expression:

$k = \frac{\ln 2}{t_{1/2}}$ (2)

Where $t_{1/2}$ is the half-life of the isotope, measured in minutes or years.

Now we proceed to determine the missing values:

a) Polonium-200 ( $t_{1/2} = 11.5\,min$ )

$k = \frac{\ln 2}{11.5\,min}$

$k \approx 0.0602\,\frac{1}{min}$

b) Lead-194 ( $t_{1/2} = 10.7\,min$ )

$k = \frac{\ln 2}{10.7\,min}$

$k \approx 0.0648\,\frac{1}{min}$

c) Iodine-125 ( $k = 0.0115\,\frac{1}{day}$ )

$t_{1/2} = \frac{\ln 2}{k}$

$t_{1/2} = \frac{\ln 2}{0.0115\,\frac{1}{day} }$

$t_{1/2} \approx 60.274\,days$

d) Kryption-75 ( $k = 0.161\,\frac{1}{min}$ )

$t_{1/2} = \frac{\ln 2}{k}$

$t_{1/2} = \frac{\ln 2}{0.161\,\frac{1}{min} }$

$t_{1/2}\approx 4.305\,min$

e) Strontium-79 ( $t_{1/2} = 2.3\,min$ )

$k = \frac{\ln 2}{2.3\,min}$

$k \approx 0.3\,\frac{1}{min}$

f) Uranium-229 ( $t_{1/2} = 58\,min$ )

$k = \frac{\ln 2}{58\,min}$

$k \approx 0.0120\,\frac{1}{min}$

g) Plutonium-239 ( $t_{1/2} = 24100\,yr$ )

$k = \frac{\ln 2}{24100\,yr}$

$k \approx 2.876\times 10^{-5}\,\frac{1}{yr}$

6 0

3 years ago

Angle 3 measures 54 degrees <br><br>What is the measure of angle 1?

mariarad [96]

Answer:

angle 1 measures 54°

Step-by-step explanation:

opposite angles are congruent

7 0

3 years ago

Write an equation to show the relationship between 7 meters and .007 kilometer

Dennis_Churaev [7]

7*0.001 = 0.007

I hope this helps!

5 0

3 years ago

By air, the distance from city a to city b is 3008 miles less than the distance from city c to city

ella [17]

The distance from city C to city D is 4,814 miles.

5 0

3 years ago