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Flura [38]
3 years ago
5

Solve the system by substitution. 3x + y = 20 -7y=x Please help

Mathematics
1 answer:
alisha [4.7K]3 years ago
8 0

9514 1404 393

Answer:

  (x, y) = (7, -1)

Step-by-step explanation:

The expression for x makes it easy to use that for substitution.

  3(-7y) +y = 20

  -20y = 20 . . . . . collect terms

  y = -1 . . . . . . . . . divide by -20

  -7(-1) = x = 7 . . . use y in the second equation to find x

The solution is (x, y) = (7, -1).

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I’m confused can ya help me
Harlamova29_29 [7]

Answer:

C & D

Step-by-step explanation:

x² + 3x - 3 = 0

a = co efficient of  x² = 1

b=  co efficient of x = 3

c = constant = -3

roots = (-b ± \sqrt{b-4ac})/2a

    = (-3±\sqrt{3^{2}-4*1*[-3]} )/2*1

    = (-3±\sqrt{9+12})/2

    = (-3±√21)/2

  x = \frac{-3+\sqrt{21}}{2}     ; x =\frac{-3-\sqrt{21}}{2}

7 0
3 years ago
At Greenwood Landscaping, rock costs $47.50 per ton. How much would 2.5 tons cost?
Grace [21]

Answer:

Hey!

Your answer is $118.75!

Step-by-step explanation: How did I get this?

<u>STEP 1:</u> So we know that for a ton of rock costs us $47.50...

To get 2 tons all we have to do is to MULTIPLY $47.50 by 2...

<em><u>(47.50 x 2 = 95)</u></em>

<u>STEP 2: </u>So for $95, you will get 2 tons of rock!

Now to get the .5 tons of rock in price form, we have to get the price of the whole 2.5 tons and DIVIDE BY 2

<em><u>(47.50 ÷ 2 = 23.75)</u></em>

<u>STEP 3:</u> So now we have the costs for 2 tons and the price for HALF a ton.

What we do now is easy...we ADD THE VALUES TOGTHER!

<em><u>(95 + 23.75 = $118.75)</u></em>

The result of $118.75 after adding them together is the PRICE OF 2 TONS!

<u>I HOPE THIS HELPED YOU!</u>

<u />

4 0
3 years ago
On the day of his 18th birthday harry decided to start saving money regularly
Veseljchak [2.6K]

We have been given that on the day of his 18th birthday Harry decided to start saving money regularly . Starting on that day, he could save 30.00 on the same date every month. We are asked to find the amount saved by the day before Harry's 60th birthday.

First of all, we will find years from 18 years to 60 years.

\text{Years}=60-18=42

We know that 1 year equals 12 months.

\text{42 years}=12\times 42\text{ Months}=504\text{ Months}

To find total amount saved, we will multiply 504 months by amount saved per month.

\text{Total amount saved}=\$30\times 504

\text{Total amount saved}=\$15,120

Therefore, Harry would have saved \$15,120 by the day before his 60th birthday.

3 0
3 years ago
A car costs $9,000. If Mr.Smith has saved 20% of this amount, how much did he save?
olga2289 [7]

Answer:

the answer for your question would be 1800

Step-by-step explanation:

you multiply 9000 times by .20

5 0
3 years ago
Read 2 more answers
What multiplies to -300 and adds to 13
Alona [7]
25 and -12 because when you subtract 12 from 25 you will get 13 and when you multiply 25 by -12 you will get -300
6 0
3 years ago
Read 2 more answers
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