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inysia [295]
3 years ago
8

Given ƒ(x) = 3x + 9, find x when ƒ(x) = 21. A) 3 B) 4 C) 7 D) 10

Mathematics
2 answers:
docker41 [41]3 years ago
7 0
X=21
21-9=12
3x=12
12divided by 3=4
X=4. The answer is B
Alborosie3 years ago
6 0

Answer:

B

Step-by-step explanation:

Replacing <em>f</em>(x) with 21, this is the equation

21=3x+9

First, subtract 9 from each side of the equation to get:

12 = 3x

Next, divide each side by 3 to get:

4 = x

So the answer is B.

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Find the value of 6.8 +9.2
Tatiana [17]

Answer:

16

Step-by-step explanation:

6.8

+9.2

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16

Hope I helped!

8 0
2 years ago
Read 2 more answers
You have one type of nut that sells for $2.80/lb and another type of nut that sells for $9.60/lb. You would like to have 20.4 lb
max2010maxim [7]

Answer:11.396Ibs of nuts that cost $9.60/Ib and 9.014Ibs that cost $2.80/Ib

Step-by-step explanation:

First we find the cost of the supposed mixture we are to get by selling it $6.60/Ib which weighs 20.41Ibs

Which is 6.6 x 20.41 = $134.64

Now we label the amount of mixture we want to get with x and y

x = amount of nuts that cost $2.8/Ib

y = amount of nuts that cost $9.6/Ib

Now we know the amount of mixture needed is 20.41Ibs

So x + y = 20.41Ibs

And then since the price of the mixture to be gotten overall is $134.64

We develop an equation with x and y for that same amount

We know the first type of nut is $2.8/Ib

So for x amount we have 2.8x

For the second type of nut that is $9.6/Ib

For y amount we have 9.6y

So adding these to equate to $134.64

2.8x + 9.6y = 134.64

So we have two simultaneous equations

x + y = 20.41 (1)

2.8x + 9.6y = 57.148 (2)

We can solve either using elimination or factorization method

I'm using elimination method

Multiplying the first equation by 2.8 so that the coefficient of x for both equations will be the same

2.8x + 2.8y = 57.148

2.8x + 9.6y = 134.64

Subtracting both equations

-6.8y = -77.492

Dividing both sides by -6.8

y = -77.492/-6.8 =11.396

y = 11.396Ibs which is the amount of nuts that cost $9.6/Ib

Putting y = 11.396 in (1)

x + y = 20.41 (1)

x +11.396 = 20.41

Subtract 11.396 from both sides

x +11.396-11.396 = 20.41-11.396

x = 9.014Ibs which is the amount of nuts that cost $2.8/Ibs

8 0
3 years ago
Solve for x (5x+12)°<br>solve for y (2y+11)°
Yuki888 [10]
You cant solve for x or y
5 0
3 years ago
3x + ky = 8
djyliett [7]

Answer:

a) 3x + ky = 8

ky = 8 - 3x

x – 2ky = 5

x - 2(8 - 3x) = 5

x - 16 + 6x = 5

7x = 21

x = 3 (shown)

b) x-2ky = 5

sub x = 3, y = 1/2

3-2k(1/2) = 5

-2k = 2

k = -1

3 0
3 years ago
Ashlyn and her friends are making gingerbread houses. They need to divide 28 packages of gumdrops between 7 friends. There are 2
leonid [27]

Answer:

100 gumdrops per person

Step-by-step explanation:

We know that there are 28 packages and each one has 25.  So just multiply 28 by 25 and you get 700 gumdrops in total.  Finally because there are seven friends in total you divide 700 by 7 and get 100 per person.

4 0
3 years ago
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