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2 years ago

Which is a factor of 5x2 − 15x − 20?

Mathematics

1 answer:

Sholpan [36]2 years ago

7 0

Answer:

x= -1, x=4

Step-by-step explanation:

5x²-15x-20

5x²-20x+5x-20=0

5x(x-4) +5(x-4)

(5x+5) (x-4) =0

5x=-5 or x=4

x= -5/5. or x=4

x= -1 or x=4

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It takes Daphne 25 minutes to assemble a model plane. During her work day Daphne takes 30 minutes for lunch and one 15 minute br

natka813 [3]

Answer:

Step-by-step explanation:

We first of all start by cumulating all the time she spent for break

lunch= 30min

break= 15min

total break= 45min

also the time taken to assemble one model plane 25min

let the number of hours be p

and the total number of model plane be y

The model is

y=25p-45

7 0

1 year ago

Lin counts 5 bacteria under a microscope. She counts them again each day for four days, and finds

svetlana [45]

Answer:

Yes, but it is not linear. It is exponential : $f(x) = 5\cdot 2^{x-1}$

Step-by-step explanation:

On the first day we have 5 bacteria.

On the second day we will have 5*2 = 10 bacteria.

On the third day we will have 10*2 = 5*2*2 = 5*2^2 = 20 bacteria.

On the fourth day we will have 20*2 = 5*2*2*2 = 5*2^3 = 40 bacteria.

We can see that

$f(x) = 5\cdot 2^{x-1}$ ,

where x is a number of days and f(x) gives us the number of bacteria.

4 0

1 year ago

79% of a university's freshman class are majoring in Engineering. If 2765 students in the freshman class are Engineering majors,

Karolina [17]

$2765 \div 0.79 = 3500$

There are 3500 students in the freshman class.

8 0

1 year ago

Read 2 more answers

A bacon cheeseburger at a popular fast food restaurant contains 2,070mg of sodium, which is 86% of the recommended daily amount.

svp [43]

2,070mg 86%
— = —
? mg 100%

Cross multiply (2,070 X 100) which equals 207,000

Then divide 207,000 by 86 which equals
2,406.976

Then you round so you get 2,407

The Answer is 2,407 milligrams

5 0

1 year ago

1 point) As reported in "Runner's World" magazine, the times of the finishers in the New York City 10 km run are normally distri

BigorU [14]

Answer:

(a) E (X) = 61 and SD (X) = 9

(b) E (Z) = 0 and SD (Z) = 1

Step-by-step explanation:

The time of the finishers in the New York City 10 km run are normally distributed with a mean,μ = 61 minutes and a standard deviation, σ = 9 minutes.

(a)

The random variable X is defined as the finishing time for the finishers.

Then the expected value of X is:

E (X) = 61 minutes

The variance of the random variable X is:

V (X) = (9 minutes)²

Then the standard deviation of the random variable X is:

SD (X) = 9 minutes

(b)

The random variable Z is the standardized form of the random variable X.

It is defined as: $Z=\frac{X-\mu}{\sigma}$

Compute the expected value of Z as follows:

$E(Z)=E[\frac{X-\mu}{\sigma}]\\=\frac{E(X)-\mu}{\sigma}\\=\frac{61-61}{9}\\=0$

The mean of Z is 0.

Compute the variance of Z as follows:

$V(Z)=V[\frac{X-\mu}{\sigma}]\\=\frac{V(X)+V(\mu)}{\sigma^{2}}\\=\frac{V(X)}{\sigma^{2}}\\=\frac{9^{2}}{9^{2}}\\=1$

The variance of Z is 1.

So the standard deviation is 1.

8 0

1 year ago