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3 years ago

Which expression is equivalent to (3b + 2r) + (4b + r)?

Mathematics

2 answers:

marysya [2.9K]3 years ago

6 0

(3b+2r)+(4b+r)=3b+4b+2r+r=7b+3r. B. 7b+3r

lozanna [386]3 years ago

4 0

To do this problem, you need to first get rid of all the parenthesis. Since all the operations are addition (+), remember the Associative Property of Addition. This property says when you're adding, it doesn't matter where you put the parentheses because it'll all add up to the same thing.

That means (3b + 2r) + (4b + r) = (3b + 4b) + (2r + r), or even, just get rid of the paratheses in general and have (3b + 2r) + (4b + r) = (3b + 2r + 4b + r).

Either way, now you can add like terms so:
(3b + 2r) + (4b + r) = (3b + 4b) + (2r + r) = 7b + 3r

Your answer is B) 7b + 3r

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A screening test for a disease shows a positive result in 91% of all cases when the disease is actually present and in 7% of all

Jobisdone [24]

Answer:

0.0713 = 7.13% probability that the result is positive.

Step-by-step explanation:

Probability of a positive test:

91% of 1/650(has the disease).

7% of 1 - 1/650 = 649/650(does not have the disease). So

$p = 0.91\frac{1}{650} + 0.07\frac{649}{650} = \frac{0.91 + 0.07*649}{650} = 0.0713$

0.0713 = 7.13% probability that the result is positive.

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2 years ago

James has 36 tulips. He must put the same number of tulips in each vase. How many tulips could be in each vase

k0ka [10]

1,2,3,4,6,9,12,18,36

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7 0

3 years ago

Read 2 more answers

A bacteria culture grows with constant relative growth rate. The bacteria count was 1,920 after 4 hours and 1,966,080 after 12 h

attashe74 [19]

From the calculation, the growth rate is 0.88.

<h3>What is the growth rate?</h3>

To find the relative growth rate

P1 = Poe^rt

P2 = Poe^rt

Thus;

1920 = Poe^4r ------ (1)

1966080 =Poe^12r -------(2)

P2/P1 gives;

1966080/1920 = Poe^12r/Poe^4r

1024 = e^12r/e^4r

1024 =e^8r

1024 = (e^r)^8

2^10 = (e^r)^8

e^r = 2^1.25

e^r = 2.38

r = ln(2.38)

r = 0.88

The initial size of the culture is;

1920 = Poe^(0.88 * 4)

Po = 1920/e^(0.88 * 4)

Po = 57

The expression for the exact number of bacteria after t hours is

P(t) = 57e^0.08t

The growth (in bacteria per hour) after 9.5 hours is

P(t) = 57e^(0.88 * 9.5)

P(t) = 243544

For the number to reach 72,000;

72,000 = 57e^0.88t

72,000/57 = e^0.88t

ln 126 = ln[e^0.88t]

4.8 = 0.88t

t = 4.8/0.88

t = 5.5 hours

Learn more about exponential growth;brainly.com/question/13674608

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8 0

2 years ago

Find the value of (-4)(6)(-7) -178 168 178 -168

kakasveta [241]

Answer:

168

Explanation:

Before we begin, remember the following:

+ve * +ve = +ve -ve * -ve = +ve

+ve * -ve = -ve -ve * +ve = +ve

Now, for the given problem we have:

(-4) * (6) * (-7)

Let's take the first two terms:

(-4) * (6)

Based on the above rules, the product will be negative

Therefore,

(-4) * (6) = -24

Now, the expression became:

(-24) * (-7)

Again, based on the above rule, the product here will be positive

Therefore,

(-24) * (-7) = 168

Hope this helps :)

4 0

3 years ago

Read 2 more answers

Mister Rogers is fencing another new rectangular garden in his neighborhood. One side of the garden faces the road and needs to

Oksanka [162]

Answer:

length of the pretty side and length of the side oppositte to the pretty side = 37.91 ft

length of the other two sides = 27.52 ft

Step-by-step explanation:

The mathematical problem is:

Max A = b1*h

subject to: 35*b1 + 18*(2*h + b2) <= 3000

Where

A: area of the garden

b1: length of the pretty side

b2: length of the side oppositte to the pretty side

h: length of the other two sides

Replacing with b1 = b2 and taking only the equality sign in the restriction (in the maximum all the money will be spent), we get:

35*b1 + 18*(2*h + b1) = 3000

35*b1 + 36*h + 18*b1 = 3000

53*b1 + 36*h = 3000

b1 = 3000/53 - (36/53)*h

Substituing in Area's formula

A = (3000/53 - (36/53)*h)*h

A = (3000/53)*h - (36/53)*h^2

In the maximum, the derivative of A is equal to zero

dA/dh = 3000/53 - 2*(36/53)*h =

3000/53 - 72/35*h = 0

h = (3000/53)*(35/72)

h = 27.52 ft

then,

b1 = 3000/53 - (36/53)*27.52

b1 = 37.91 ft =b2

3 0

3 years ago