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Vanyuwa [196]
3 years ago
9

Which expression is equivalent to 4.2a−2(0.4a−1.3)

Mathematics
2 answers:
Serggg [28]3 years ago
8 0
Is the answer 4a+1.3
Sati [7]3 years ago
3 0

Answer:

the 3rd one

Step-by-step explanation:

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I have $1.00 in coins. One-fifth of the coins are dimes, two-fifteenth are nickels, and two-thirds are pennies. How many of coin
dmitriy555 [2]
You would have 30 coins,  6 dimes, 4 nickels, and 20 pennies.
3 0
4 years ago
A ball is thrown upward and outward from a height of 77 feet. the height of the​ ball, f(x), in​ feet, can be modeled by f left
Oksi-84 [34.3K]
From the given function modeling the height of the ball:
f(x)=-0.2x^2+1.4x+7
A] The maximum height of the ball will be given by:
At max height f'(x)=0
from f(x), 
f'(x)=-0.4x+1.4
solving for x we get:
-0.4x=-1.4
x=3.5ft
thus the maximum height would be:
f(3.5)=-0.2(3.5)^2+1.4(3.5)+7
f(3.5)=9.45 ft

b]
How far from where the ball was thrown did this occur:
from (a), we see that at maximum height f'(x)=0
f'(x)=-0.4x+1.4
solving for x we get:
-0.4x=-1.4
x=3.5ft
This implies that it occurred 3.5 ft from where the ball was thrown.


 c] How far does the ball travel horizontally?
f(x)=-0.2x^2+1.4x+7
evaluationg the expression when f(x)=0 we get:
0=-0.2x^2+1.4x+7
Using quadratic equation formula:
x=-3.37386 or x=10.3739
We leave out the negative and take the positive answer. Hence the answer 10.3739 ft horizontally.
6 0
4 years ago
Geno started to evaluate 90 − (18 + −2)(−3), as shown. What should he do next?
alexira [117]

90 - (18 +  - 2)( - 3) \\  \\ =  90 - (16)( - 3) \\  \\  = 90 - ( - 48) \\  \\ =  138
First, you take 18 minus 2
Then you multiply 16 by -3
And take 90 minus -48
4 0
3 years ago
Read 2 more answers
Plz help<br>math question ​
stiks02 [169]

Answer: 0, I think?

Step-by-step explanation: In order to do this equation, we want to get the variable on one side. In order to do this, we add 7 to both sides to cancel out the -7's. Now, we divide 9 on both sides, giving us 0.

6 0
3 years ago
Usebthe elimination method to solve the following system of equations<br>4x+y=13<br>5x-y=5​
pochemuha

Answer:

x = -2, y = 21

Step-by-step explanation:

Let 4x + y = 13 to be equation1 {eqn1}

and let 5x - y = 5 to be equation2 {eqn2}

Using elimination method, you would try to make sure a particular unknown has the same value in both equation 1 and 2. This would make it easy for you to subtract one equation from the other.

Notice how the value of y is the same in both equations. That's a good sign.

But the signs aren't the same. Meaning y in eqn1 has a value of +1, and y in eqn2 has a value of -1. We need to make them similar.

So, we multiply the value of y in eqn1 by all the terms in eqn2. And, do pretty much the same thing by multiplying the value of y in eqn2 by all the terms in eqn1.

You would have:

-1 * (4x + y = 13)

+1 * (5x - y = 5)

This would result in;

-4x -  y = -13 (eqn3)

5x - y = 5 (eqn4)

So, just subtract eqn3 from 4

You would have;

(5x - -4x) + (-y -- y) = (-13 - 5)

9x + 0 = -18

x = -18/9 = -2

and to find y;

just substitute the value of x into any of the 4 equations. let's try equation 1

Therefore;

4(-2) + y = 13

-8 + y = 13

y = 13 + 8 = 21

8 0
3 years ago
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