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3 years ago

1. Girl Scout Troop 321 started with 25 girls and at the end of the year party there were 31 girls. Gabby

Mathematics

1 answer:

Oksanka [162]3 years ago

3 0

Answer: 24%

Step-by-step explanation:

Since we are informed that the Girl Scout Troop started with 25 girls and at the end of the year party there were 31 girls. The percentage change will be:

= (31 - 25) / 25 × 100

= 6/25 × 100

= 24%

The error that Gabby made was that she used 31 as the base. This is expressed below:

= 31 - 25) / 31 × 100

= 6/31 × 100

= 19.4%

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Please help me with 1,2,3,show me how you get the answers and show me the steps for 1,2,3,please do not send me link write it ri

Natali [406]

Answer:

Step-by-step explanation:

1. ok so you need to use Pythagoras which is a^2 + b^2 = c^2

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3 years ago

Can someone help me please? Use the linear combination method to solve the system of equations. Pretty please show your work and

Pavel [41]

Answer:

(x, y) = (4, -3)

Step-by-step explanation:

x-3y=13
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First of all, look at the given equations. Here, we see that the second equation has coefficients that all have a factor of 2. If we divide that out, we get an equation that has an x-coefficient of 1, matching the x-coefficient in the first equation.

Here is the reduced second equation:

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We note that the y-coefficient in the first equation is less than that in the second equation. If we subtract the first equation from the second, the result will have a positive y-coefficient:

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I find a graphing calculator provides an easy and reliable check of the answer.

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Comment on linear combination

This method is often called "elimination," because the purpose of combining the equations in a particular way is to eliminate one of the variables. This requires you look at the coefficients of the variables and devise a plan to combine them so the resulting coefficient for one of the variables is zero.

In the worst case, you can combine ...

ax +by = c
dx +ey = f

by multiplying the second equation by a and the first by -d:

a(dx +ey) -d(ax +by) = a( f) -d(c)

y(ae -bd) = fa -cd . . . . . . simplify; x is eliminated

This sort of approach results in a formula for the solution known as Cramer's Rule.

y = (fa-cd)/(ae-bd)

The corresponding solution for x is ...

x = (ce-bf)/(ae-bd)

The point of looking at the equations first is that you can often choose which variable to eliminate and what multiplier to use to minimize the amount of arithmetic involved—as we did above.

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25. Tiffany deposited two checks into her account this month. One check was for $70 and the second was for $25. Her balance at t

Anna35 [415]

The first thing to do is to start with something not quite so

complicated, so you can get used to the ideas first. But let's go

ahead with this one, to check your work.

Here's one way I write these to demonstrate how to think it through:

(18/2){[(9 x 9 - 1)/ 2]-[5 x 20 - (7 x 9 - 2)]}

\____/ \_________/ \_________/

9 {[ 80 / 2]-[5 x 20 - 61 ]}

\______________/ \____________________/

9 { 40 - 39 }

\_______________________________________/

9 * 1

\____________________/

So you're correct, and your work was fine. The only thing I did

differently was to evaluate 18/2 earlier, because nothing stood in its

way; I could have waited as you did.

What parentheses do is to contain a subexpression that has to be fully

evaluated before it can be used in any containing expression. That's

why you work from the inside out: you can't use what's inside until

you evaluate it all, so you might as well start there. But if you

forgot to, you'd still have a reminder. Here's an example:

2[(3 + 7)(3 - 2) - 3(2 + 2)]

If I didn't bother with the inside-out "rule", I might just start

trying to evaluate at the left (paying attention to the order of

operations, of course): 2 times ... what? Well, the second number in

that multiplication is the whole thing inside [...], so I have to put

it on hold until I do that. So I focus on

(3 + 7)(3 - 2) - 3(2 + 2)

Now I start that. The first piece is (3 + 7), so I evaluate that

whole thing and get 10. Now I have to multiply it by (3 - 2), so I

stop and evaluate that, which gives 1. Now I can multiply 10 by 1 and

get 10. So I keep going; I have to subtract something from that, but

since the next bit is a product, I have to do that first. I'll have 3

times the next parenthesis; that's 3 times 4, so I have 12. The

subtraction I put off is 10 - 12 = -2.

Now, this is what the whole [...] is, so I go back and do that last

multiplication:

2*(-2) = -4

7 0

3 years ago