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belka [17]
2 years ago
10

HELPPP!!!!!

Mathematics
2 answers:
garik1379 [7]2 years ago
7 0

Answer:

Nicole is correct, since when she multiplied by 3, she cleared the x's, since one x was already negative, and the other one was positive. Michael is incorrect since when he multiplied by 2, he didn't realize that both y's were positive, so they didn't clear.

Step-by-step explanation:

Let's see what will happen if we do what Nicole says:

x+2y=7

-3x+4y=9

multiply the first equation by 3 on both sides

3(x+2y)=7(3)

3x+6y=21

-3x+4y=9

now let's add them.

10y=30

We can see that the x's are cleared, since one x is positive and the other is negative.

Now let's try what Michael says.

x+2y=7

-3x+4y=9

multiply first equation by 2

2(x+2y)=7

2x+4y=7

-3x+4y=9

now let's add

-x+8y=16

the y's aren't eliminated, since both of them are positive.

Nicole is correct, since one x is positive and another was negative, and when opposite numbers are added together, they  cancel out and equal zero.

Hope this helps!

Kaylis [27]2 years ago
5 0

Answer:

Nicole is correct

Step-by-step explanation:

by multiplying the first equation by 3 it becomes:

3x + 6y =21

this can cancel the -3x in the second equation when adding them together

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I need to answer the two questions at the bottom please help.
Nookie1986 [14]
1st question

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3 years ago
A cubed-shaped box has its side lengths decreased by 3 cm, when this happens, the volume decreases by 1385cm^3. What is the side
mixer [17]

Answer:

Step-by-step explanation:

let side of cube=x cm

volume=x³ cm³

again side=(x-3) cm

volume=(x-3)³ cm³

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(x-x+3){x²+x(x-3)+(x-3)²}=1385

3(x^2+x²-3x+x²-6x+9)=1385

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x=\frac{27\pm\sqrt{(-27)^2-4*9*(-1358)} }{2*9} \\x=\frac{27\pm\sqrt{729+48888} }{18} \\or~x=\frac{27\pm\sqrt{49617} }{18} \\or~x=\frac{27\pm 222.749}{18} \\taking positive side only as negative sign gives negative length.\\or~x=\frac{27+222.749}{18} \\or~x\approx13.87

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3 years ago
The number of bacteria in a certain culture doubled every hour. If there were 30 bacteria present in the culture initially, how
vichka [17]

Answer:

The number of bacteria after 8th will be 3840

Step-by-step explanation:

Given the initially 30 bacteria present in the culture.

Also, the number of bacteria got doubled every hour.

So, using the equation

A=A_0r^{n-1}

Where A is number of bacteria after n hours.

A_0 is bacteria present initially.

r is the common ration, in our problem it is given that bacteria doubles every hour. So, r=2

And n is the number of hours. In our problem we need amount of bacteria at the end of 8th hours. So, n=8

Plugging values in the formula we get,

A=30(2)^{8-1}\\A=30\times 2^7\\A=30\times 128\\A=3840

So, number of bacteria after 8th will be 3840

3 0
3 years ago
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