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tigry1 [53]
4 years ago
6

An inner city revitalization zone is a rectangle that is twice as long as it is wide. The width of the region is growing at a ra

te of 40 m per year at a time when the region is 290 m wide. How fast is the area changing at that point in time?
Mathematics
1 answer:
Reil [10]4 years ago
6 0

Answer:

20

Step-by-step explanation:

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Given the function, f(x) = x2 - 3, calculate the average rate of change of the function from x = 1 to x = 3.
Crank

\bf slope = m = \cfrac{rise}{run} \implies  \cfrac{ f(x_2) - f(x_1)}{ x_2 - x_1}\impliedby  \begin{array}{llll} average~rate\\ of~change \end{array}\\\\ -------------------------------\\\\ f(x)= x^2-3  \qquad  \begin{cases} x_1=1\\ x_2=3 \end{cases}\implies \cfrac{f(3)-f(1)}{3-1} \\\\\\ \cfrac{[3^2-3]-[1^2-3]}{2}\implies \cfrac{6 - (-2)}{2}\implies \cfrac{6+2}{2}\implies \cfrac{8}{2}\implies 4

7 0
3 years ago
Read 2 more answers
A train leaves San Diego at 1:00 pm. A second train leaves the same city in the same direction at 3:00 pm. The second train trav
Soloha48 [4]

Answer:

The speed of the first train is 45 mph and the speed of the second train is 75 mph

Step-by-step explanation:

Let x represent the speed of the first train in mph. Since the second train, is 30 mph faster then the first, therefore the speed of the second train is (x + 30).

The first train leaves at 1:00 pm, therefore at 6:00 pm, the time taken is 5 hours. Therefore the distance covered by the first train at 6:00 pm = x mph * 5 hours = 5x miles

The second train leaves at 3:00 pm, therefore at 6:00 pm, the time taken is 3 hours. Therefore the distance covered by the second train at 6:00 pm = (x + 30) mph * 3 hours = (3x + 90) miles

Since the second train overtakes the first at 6:00 pm, hence:

3x + 90 = 5x

2x = 90

x = 45

Therefore the speed of the first train is 45 mph and the speed of the second train is 75 mph (45 mph + 30 mph).

7 0
3 years ago
John has two colored varieties of water bottles: white water bottles and black water bottles. The total number of water bottles
mixas84 [53]

Answer:

15 black water bottles

Step-by-step explanation:

let w represent white water bottles, and let b represent black water bottles.

set up a system of equations:

w+b=20

w+2b=35

(the top equation shows that the number of white water bottles he sold and the number of black water bottles he sold equals to 20, since it says that the total number of water bottles is 20. the bottom equation shows that white water bottles cost $1, and black water bottles cost $2, and that the total amount of money he got from selling them is $35).

in the top equation, isolate w:

w+b=20

w=20-b

now we do substitution. in the bottom equation, substitute 20-b for w:

w+2b=35

20-b+2b=35

then, solve:

b+20=35

b=15

this means that he sold 15 black water bottles.

4 0
3 years ago
Bob’s age is 15 years less than half his father’s age. In six years his father’s age will be eleven years more than triple Bob’s
d1i1m1o1n [39]

His father's age is 44 years

Step-by-step explanation:

The given is:

  • Bob’s age is 15 years less than half his father’s age
  • In six years his father’s age will be eleven years more than triple Bob’s age

We need to find his father’s age now

Assume that the Father's age is x years

∵ The father's age is x years

∵ Bob’s age is 15 years less than half his father’s age

- That means multiply x by half and subtract 15 from it

∴ Bob's age = \frac{1}{2} x - 15

In six years

The father's age = x + 6

The Bob's age = \frac{1}{2} x - 15 + 6 = \frac{1}{2} x - 9

∵ In six years his father’s age will be eleven years more than

   triple Bob’s age

- That means equate (x + 6) by 3 times Bob's age and add 11

   to the product

∴ x + 6 = 3( \frac{1}{2} x - 9) + 11

- Simplify the right hand side

∴ x + 6 = \frac{3}{2} x - 27 + 11

- Add like terms in the right hand side

∴ x + 6 = \frac{3}{2} x -16

- Subtract 6 from both sides

∴ x = \frac{3}{2} x - 22

- Subtract \frac{3}{2} x from both sides

∴ \frac{-1}{2} x = -22

- Divide both sides by \frac{-1}{2}

∴ x = 44

His father's age is 44 years

Learn more;

You can learn more about the world problems in brainly.com/question/12148432

#LearnwithBrainly

5 0
3 years ago
A first number plus twice a second number is 8 twice the first number plus the second totals 25
Orlov [11]

Answer:

x=14 y=-3

Step-by-step explanation:

7 0
3 years ago
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