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3 years ago

Help me!!!!! Simplify (7)(-6).

Mathematics

1 answer:

mash [69]3 years ago

4 0

Answer:

-42

Step-by-step explanation:

Multiply

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2.The number of grams A of a certain radioactive substance present at time, in yearsfrom the present, t is given by the formulaA

professor190 [17]

Answer:

Given that,

The number of grams A of a certain radioactive substance present at time, in years

from the present, t is given by the formula

$A=45e^{-0.0045(t)}$

a) To find the initial amount of this substance

At t=0, we get

$A=45e^{-0.0045(0)}$ $A=45e^0$

We know that e^0=1 ( anything to the power zero is 1)

we get,

$A=45$

The initial amount of the substance is 45 grams

b)To find thehalf-life of this substance

To find t when the substance becames half the amount.

A=45/2

Substitute this we get,

$\frac{45}{2}=45e^{-0.0045(t)}$

$\frac{1}{2}=e^{-0.0045(t)}$

Taking natural logarithm on both sides we get,

$\ln (\frac{1}{2})=-0.0045(t)^{}$ $(-1)\ln (\frac{1}{2})=0.0045(t)$ $\ln (\frac{1}{2})^{-1}=0.0045(t)$ $\ln (2)=0.0045(t)$ $0.6931=0.0045(t)$ $t=\frac{0.6931}{0.0045}$ $t=154.02$

Half-life of this substance is 154.02

c) To find the amount of substance will be present around in 2500 years

Put t=2500

we get,

$A=45e^{-0.0045(2500)}$ $A=45e^{-11.25}$ $A=45\times0.000013=0.000585$ $A=0.000585$

The amount of substance will be present around in 2500 years is 0.000585 grams

4 0

1 year ago

Find the y-intercept for the parabola defined by this equation y=5x2-x-6

bija089 [108]

Y intercept is -6

Y= 5x^2-X-6
Y= 5(0)^2-0-6
Y= 0-0-6

7 0

3 years ago

On cold days Leah likes to make hot chocolate. She uses 8 tablespoons of cocoa and 2 tabelspoons of sugar, what ratio is equival

galben [10]

Answer:

4 to 1

Step-by-step explanation:

The greatest common factor between 8 and 2 is 2. So 2 will go into 8, 4 times. And 2 will go into 2, 1 time. So simplified the equivalent ratio is 4:1.

8 0

3 years ago

Solve this step by step

Kaylis [27]

Step-by-step explanation:

the formula to calculate a circumference is

$x \times \pi$