Brainiest if correct please help!!!

Strontium-90 has a half-life of 28.8 years. If you start with a 300-gram sample of strontium-90,

Kazeer [188]

Answer: 2.66 × 10⁻¹³

<u>Step-by-step explanation:</u>

First, use the decay formula $A=A_oe^{kt}$ where

A is the final amount (amount left)
A₀ is the initial amount (amount you started with)
k is the rate of decay (you need to solve for this)
t is the time

Given:

A = 1/2(300) = 150
A₀ = 300
k = unknown
t = 28.8

$150=300e^{28.8k}\\\\0.5=e^{28.8k}\\\\ln(0.5)=ln(e^{28.8k})\\\\ln(0.5)=28.8k\\\\\\\dfrac{ln(0.5)}{28.8}=k\\\\\\\large\boxed{-0.0240676=k}\\$

Next, input the k-value and the new t-value to solve for A.

A = unknown
A₀ = 300
k = -0.0240676
t = 1440

$A=300e^{1440(-.0240676)}\\\\\large\boxed{A=2.66\times 10^{-13}}\\$

5 0

3 years ago

els 9, Gaps, and Peaks on a Dot Plot Runs Scored Per Game The dot plot shows the number of runs scored by the boy's baseball tea

STatiana [176]

Answer:

ciu4rhiydve

Step-by-step explanation:

mrclutch master on fortnite add me yoclapz_yt

6 0

2 years ago

Read 2 more answers

The graph of the quadratic function y=-x^2-2x+3 is shown below

Karolina [17]

Answer:

The axis of symmetry is at $x=-1$

The graph has an x-intercept at $(1,0)$

The graph has a vertex at $(-1,4)$

Step-by-step explanation:

we have

$y=-x^{2}-2x+3$

Statements

case 1) The graph has root at $3$ and $1$

The statement is False

Because, the roots of the quadratic equation are the values of x when the value of y is equal to zero (x-intercepts)

Observing the graph, the roots are at $-3$ and $1$

case 2) The axis of symmetry is at $x=-1$

The statement is True

Observing the graph, the vertex is the point $(-1,4)$

The axis of symmetry in a vertical parabola is equal to the x-coordinate of the vertex

so

the equation of the axis of symmetry is $x=-1$

case 3) The graph has an x-intercept at $(1,0)$

The statement is True

see procedure case 1)

case 4) The graph has an y-intercept at $(-3,0)$

The statement is False

Because, the y-intercept is the value of y when the value of x is equal to zero

Observing the graph, the y-intercept is the point $(0,3)$

case 5) The graph has a relative minimum at $(-1,4)$

The statement is False

Because, is a vertical parabola open downward, therefore the vertex is a maximum

The point $(-1,4)$ represent the vertex of the parabola, so is a maximum

case 6) The graph has a vertex at $(-1,4)$

The statement is True

see the procedure case 5)

see the attached figure to better understand the problem

6 0

3 years ago

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11 You are renting a car for a trip. You call two different rental car places about prices. Each

Sonja [21]

Answer:

Step-by-step explanation:

m is number of miles

A: 45+0.21m (45 is the initial cost)

B: 28+0.38m (28 is the initial cost)

To know how in many miles the cost will be equal,

45+0.21m=28+0.38m

0.38m-0.21m=45-28

0.17m=17

m=17/0.17 = 100

So, at 100 miles the cost will be same for company A and B.

4 0

3 years ago

Graph -5x-8y=40

Triss [41]

Answer:

Please, see the attached file.

Thanks.

Step-by-step explanation:

-5x-8y=40

This is a linear equation, and its graph is a right line, we only need two points, because by two points only goes trough only a right line:

1) For x=0→ -5(0)-8y=40

0-8y=40

-8y=40

Dividing both sides of the equation by -8:

-8y/(-8)=40/(-8)

y=-5

Point=(x,y)→Point=(0,-5)

2) For y=0→ -5x-8(0)=40

-5x-0=40

-5x=40

Dividing both sides of the equation by -5:

-5x/(-5)=40/(-5)

x=-8

Point=(x,y)→Point=(-8,0)

With these two points (0,-5) and (-8,0) we can draw the right line.

8 0

3 years ago