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gladu [14]
3 years ago
9

Evaluate the function. f(x) = -4x^2+9Find f(-3)

Mathematics
2 answers:
Svetlanka [38]3 years ago
5 0

Answer:

-27

Step-by-step explanation:

  1. f(x) = -4x² + 9
  2. f(-3) = -4(-3)² + 9
  3. f(-3) = -4(9) + 9
  4. f(-3) = -36 + 9
  5. f(-3) = -27
svetlana [45]3 years ago
4 0

Answer:

f(-3)=-27

Step-by-step explanation:

So we have the function:

f(x)=-4x^2+9

And we want to find f(-3).

So, let's substitute -3 for x. Therefore:

f(-3)=-4(-3)^2+9

Square:

f(-3)=-4(9)+9

Multiply:

f(-3)=-36+9

Add:

f(-3)=-27

And we're done!

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A cup of coffee contains about 100 mg of caffeine. Caffeine is metabolized and leaves the body at a continuous rate of about 12%
Mamont248 [21]

Answer:

a. A = C_{0}(1-x)^t\\x: percentage\ of \ caffeine\ metabolized\\

b. \frac{dA}{dt}= -11.25 \frac{mg}{h}

Step-by-step explanation:

First, we need tot find a general expression for the amount of caffeine remaining in the body after certain time. As the problem states that every hour x percent of caffeine leaves the body, we must substract that percentage from the initial quantity of caffeine, by each hour passing. That expression would be:

A= C_{0}(1-x)^t\\t: time \ in \ hours\\x: percentage \ of \ caffeine\ metabolized\\

Then, to find the amount of caffeine metabolized per hour, we need to differentiate the previous equation. Following the differentiation rules we get:

\frac{dA}{dt} =C_{0}(1-x)^t \ln (1-x)\\\frac{dA}{dt} =100*0.88\ln(0.88)\\\frac{dA}{dt} =-11.25 \frac{mg}{h}

The rate is negative as it represents the amount of caffeine leaving the body at certain time.

3 0
3 years ago
Simplify the following expression:
Phantasy [73]
\frac{4}{ \frac{1}{4} - \frac{5}{2} }

To begin, we can simplify the expression's denominator by finding a common denominator between the denominators of the fractions in the denominator.  To make them compatible, we can convert \frac{5}{2} into \frac{10}{4}:

\frac{4}{ \frac{1}{4} - \frac{5}{2}( \frac{2}{2}) } = \frac{4}{ \frac{1}{4} - \frac{10}{4} }

Next, we can simplify:

\frac{4}{ \frac{1}{4} - \frac{10}{4} } = \frac{4}{ -\frac{9}{4}}

Finally, to cancel the denominator within the denominator, we can multiply the whole expression by \frac{4}{4}, or 1:

\frac{4}{ -\frac{9}{4}}* \frac{4}{4} =  -\frac{16}{9}

The expression simplifies to -\frac{16}{9}, or -1 \frac{7}{9} as a mixed number.
6 0
3 years ago
Read 2 more answers
Describe a relationship in which one quantity increases as another quantity decreases
Morgarella [4.7K]
Inversely proportional
4 0
3 years ago
Kassie recorded the favorite sport of students at her school. She surveyed 800 students. How many more students chose Baseball t
lisov135 [29]

Answer:

40 more kids chose baseball over basketball.

Step-by-step explanation:

The best way to go about this is to use benchmark percentages.

For baseball, 25% of 800 people chose that, so we can do 800/4 to get 200, so 200 students chose baseball

For basketball, we could do 800/5 but that isn't mental math, so we can do 10% of 800 is 80 and 80*2=160. So 40 more kids chose baseball over basketball.

6 0
3 years ago
9y^2-6y+1=0<br> FIND Y PLEASE HELP STEP BY STEP
dlinn [17]

Answer:

y = 1/3

Step-by-step explanation:

<u>Step 1:  Factor</u>

9y^2 - 6y + 1 = 0

(3y - 1)(3y - 1) = 0

(3y - 1)^2 = 0

<u>Step 2:  Solve for y</u>

3y - 1 + 1 = 0 + 1

3y / 3 = 1 / 3

y = 1/3

Answer: y = 1/3

4 0
3 years ago
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