ik ik this is the last one lol
but I really need this ​

Answer:

If you have a quantity X of a substance, with a decay constant r, then the equation that tells you the amount of substance that you have, at a time t, is:

C(t) = X*e^(-r*t)

Now, we know that:

We have 2000g of substance A, and it has a decay constant of 0.03 (i assume that is in 1/year because the question asks in years)

And we have 3000 grams of substance B, with a decay constant of 0.05.

Then the equations for both of them will be:

Ca = 2000g*e^(-0.03*t)

Cb = 3000g*e^(-0.05*t)

Where t is in years.

We want to find the value of t such that Ca = Cb.

So we need to solve:

2000g*e^(-0.03*t) = 3000g*e^(-0.05*t)

e^(-0.03*t) = (3/2)e^(-0.05*t)

e^(-0.03*t)/e^(-0.05*t) = 3/2

e^(t*(0.05 - 0.03))  = 3/2

e^(t*0.02) = 3/2

Now we can apply Ln(x) to both sides, and get:

Ln(e^(t*0.02)) = Ln(3/2)

t*0.02 = Ln(3/2)

t = Ln(3/2)/0.02 = 20.3

Then after 20.3 years, both substances will have the same mass.

Answer:

6.4 laps

Step-by-step explanation:

Complete question is;

Find the exact values of the six trigonometric functions 0 if the terminal side of 0 in standard position contains the points(-5,-4).

Answer:

Sin θ = -4/√41

Cos θ = -5/√41

tan θ = 4/5

Cosec θ = (√41)/-4

Sec θ = (√41)/-5

Cot θ = 5/4

Step-by-step explanation:

Now, we are given the point (-5, -4)

These are x and y points.

They will form a triangle and we know that from pythagoras theorem;

x² + y² = r²

Where r is the distance between the point and the origin

Thus;

r² = (-5)² + (-4)²

r² = 25 + 16

r = √41

So, y is the opposite side of the triangle while x is the adjacent side with r being the hypotenuse.

Thus, the trigonometric ratios are;

Sin θ = opp/hyp = -4/√41

Cos θ = adj/hyp = -5/√41

tan θ = opp/adj = -4/-5 = 4/5

Cosec θ = 1/Sin θ = 1/(-4/√41) = (√41)/-4

Sec θ = 1/cos θ = 1/(-5/√41) = (√41)/-5

Cot θ = 1/tan θ = 1/(4/5) = 5/4

Answer:

ok i'll help just send me the question :)

Step-by-step explanation:

Answer:

what's wrong

Step-by-step explanation:

Answer:

Step-by-step explanation:

25

Answer:

20

Step-by-step explanation:

Because if 120 lasts 1/2 a year which is equivalent to 6 months you do 120 divided by 6 and get 20 hope this helps

Answer:

120/6 = 20 paper towels per month

Step-by-step explanation:

half a year is 6 months

120 divided by 6 is 20

Answer:

1) cos (140°-(50°+30°)) = 1/2

2)  [tex]sin255^{\circ}=\frac{-\sqrt{2}-\sqrt{6} }{\sqrt{4} }[/tex]

3)  [tex]cos150^{\circ}=-\frac{ \sqrt{3} }{2}[/tex]

4) ,  [tex]tan 240^{\circ}=\sqrt{3}[/tex]

Step-by-step explanation:

1) cos (140°-(50°+30°))

Solving:

cos (140°-(50°+30°))

=cos(140°-80°)

=cos(60°)

=1/2

So, cos (140°-(50°+30°)) = 1/2

2) sin 255°

We can write sin 255° as sin(180°+75°)

Solving sing formula sin(a+b)=sin(a)cos(y)+cos(x)sin(y)

[tex]sin(180^{\circ}+75^{\circ})\\=sin(180^{\circ})cos(75^{\circ})+cos(180^{\circ})sin(75^{\circ})\\=0(cos(75^{\circ}))+(-1)(\frac{\sqrt{2}+\sqrt{6} }{\sqrt{4} } )\\=0+(-1)(\frac{\sqrt{2}+\sqrt{6} }{\sqrt{4} } )\\\=\frac{-\sqrt{2}-\sqrt{6} }{\sqrt{4} }[/tex]

So, [tex]sin255^{\circ}=\frac{-\sqrt{2}-\sqrt{6} }{\sqrt{4} }[/tex]

3) cos 150°

We can solve this using the identity: cos(x)=sin(90°-x)

Solving:

cos 150°= sin(90°-150°)

=sin(-60°)

We know sin(-x)=-sin(x)

=-sin(60°)

=[tex]-\frac{ \sqrt{3} }{2}[/tex]

So, we get [tex]cos150^{\circ}=-\frac{ \sqrt{3} }{2}[/tex]

4) tan 240°

We know tan(180°+x)=tan(x)

tan 240° can be written as tan(180°+60°)

Using the above identity:

tan(180°+60°)=tan(60°) = [tex]\sqrt{3}[/tex]

So,  [tex]tan 240^{\circ}=\sqrt{3}[/tex]

Answer:

here ya go

Step-by-step explanation:

Answer:

12.5 hours

Step-by-step explanation:

Answer:

it will take Lisa 12.5 hours

Step-by-step explanation:

first figure out how many minutes it takes her per apartment.

in 2.5 hours is 150 minutes so divide 150 by 6 = 25

So, it takes her 25 minutes per apartment.

next, find out how many minutes it takes her to clean 30 apartments by:

30* 25= 750 minutes for 30 partments

divide 750 by 60 to find out how many hours

12.5 hours.

Answer:

Step-by-step explanation:

1) e) -3 - (-1) = -3 + (+1)  = -2

f) [tex]3\frac{7}{8}- (-1\frac{1}{4}) = \frac{31}{8}-(-\frac{5}{4})\\[/tex]

                     [tex]= \frac{31}{8} + (+\frac{5}{4})\\\\= \frac{31}{8} + \frac{5*2}{4*2}\\\\= \frac{31}{8} + \frac{10}{8}\\\\= \frac{31+10}{8}\\\\= \frac{41}{8}\\\\= 5\frac{1}{8}[/tex]

Given:

Sum of three consecutive integers is more than 62.

To find:

The inequality to represent the above  situation then solve your inequality.

Solution:

Let the three consecutive integers are [tex]x,x+1,x+2[/tex] respectively.

Sum of three consecutive integers is more than 62. So,

[tex]x+(x+1)+(x+2)>62[/tex]

[tex]3x+3>62[/tex]

Subtract 3 from both sides.

[tex]3x>62-3[/tex]

[tex]3x>59[/tex]

Divide both sides by 3.

[tex]x>\dfrac{59}{3}[/tex]

Therefore, the required inequality is [tex]x+(x+1)+(x+2)>62[/tex] and solution is [tex]x>\dfrac{59}{3}[/tex].

Answer:

14). 2nd quadrant

15). 1st quadrant

Step-by-step explanation:

14).Coordinates of a point → J(-8, -12)

    Coordinates of the new point J' after reflection of x-axis will follow the rule,

    (x, y) → (x, -y)

    Coordinates of J' → (-8, 12)

    Therefore, point J' will lie in 2nd quadrant.

15). Coordinates of a point → W(-6, 7)

    Rule for the rotation by 90°clockwise about the origin,

    (x, y) → (y, -x)

    Coordinates of point W → (-6, 7)

    Following this rule,

    W(-6, 7) → W'(7, 6)

    Therefore, point W' will lie in the first quadrant.

Answer:

18/8 = x/3

x = 6.75 inches (length)

Step-by-step explanation:

A larger rectangle has a length of 18 inches and width of 8 inches.

Inches /width = 18/8

So, for a rectangle that has a length of x inches and width of 3 inches the ratio is :

x/3

Solving for x:

18/8 = x/3

18/8 (3) =x

6.75 in= x

Feel free to ask for more if needed or if you did not understand something.

Answer:

SAS

Step-by-step explanation:

Answer:

it’s the first one

Step-by-step explanation:

Answer:

The correct answer is 120 students!

Step-by-step explanation:

There is a proportion you need to write down to solve it but i don’t know how to write it on here!

Answer:

There are NO wholes in 1/8.

If it were 8/8, then it would be equal to 1 whole. Since it is only 1/8, there is non wholes.

Answer:

5:4

Step-by-step explanation:

Answer:

5:4

Step-by-step explanation:

3 shirts (red)

4 shirts (blue)

3+4=7-12=5

5 shirts (white)

Answer:

Um finish the question but if its how much does he have left, its none.

Step-by-step explanation:

Didn't finish question and the reason why it's none well (-10), is because he had $200.000 than got 200=10 taken away.

Answer: x=0

Step-by-step explanation:

Answer:

105

Step-by-step explanation:

180 - 75 = 105

Answer:  

copy and paste this  link that imma put under your question I’m not really good at this but this video no cap help and others sorry hope this helps

Answer:

10cm - 7cm = 3cm

this 3cm is the decrease in the depth of water, let us find the percentage decrease.

%decrease=(decrease÷original depth) × 100%

%decreas=(3cm÷10cm)×100%

therefore we get 30%

Answer:

It will cost $5.41

Step-by-step explanation:

You would take 5% of 5.15 since that is the price of the coffee with is about 0.26 cent than you add that to the cost of the coffee.

Answer:

Step-by-step explanation:

X=2.25

Ur welcome

Answer:

Step-by-step explanation:

4/9*x=1

x=9/4 The reciprocal of 4/9 is 9/4 and makes 1 whole.

**reciprocal is a mathematical expression or function so related to another that their product is one; the quantity obtained by dividing the number one by a given quantity

Answer:

61

Step-by-step explanation:

52 + 12 = 64

64-3 that left is 62 cars in the parking lot

There are 61 cars in the parking lot.

52 + 12 = 64

64  -  3 = 61

I hope this helps, if it did, please mark brainliest and have an amazing rest of your day. Stay safe! xx

Answer:

C) 1022 1/4 square feet

Step-by-step explanation:

2L+2W=134 (perimeter)

23.5*2+2L=134

L=(134-47)/2

L=87/2=43.5 feet

A=L*W

A=(43.5)*(23.5) ft squared

A=1022.25 square feet

We know, a number is divisible by 9 if the sum of digits is also divisible by 9.

Also, since A is an digit, so A is in between 0 to 9.

2+A+5+A+0+A+2  = 3A + 9

3A + 9 should be divisible by 9.

3A + 9 = 9n

A = (9n -9)/3

For n= 1 :

A = 0

For n=2 :

A = 3

For n= 3 :

A = 9

After this A > 9 which is not accepted.

Therefore, the digit A can be 0, 3 and 9 .

Hence, this is the required solution.

The digit A that makes 2A5A0A2 to be divisible by 99 is;

A = 3

A is a single digit and as such will be between 0 and 9.

Thus, using the principle above;

2 + A + 5 + A + 0 + A + 2  = 3A + 9

3A + 9 must be divisible by 9.

Thus;

3A + 9 = 9x

A = (9x - 9)/3

When x = 1;

A = 0

When x = 2;

A = 3

When x = 3;

A = 9

Read more at; https://brainly.com/question/19299358

Answer:

5/4

Step-by-step explanation:

Lets suppose a quantity A that has a value of x

A = x

25% of A is = x/4

now adding this 25% to get 25% increase in the original value

A' = x+ x/4

    A' = 5x/4

    A' = 5*A/4

This means that , in order to increase the value by 25%  in a single step we must multiply the the original value by 5/4.