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3 years ago

What is the value of the expression 2x^2 + 3xy - 4y^2 when x = 2 and y = -4?

Mathematics

1 answer:

Vera_Pavlovna [14]3 years ago

5 0

Answer:

-80

Step-by-step explanation:

2x^2 + 3xy - 4y^2

x = 2 | y = - 4

2(2)^2 + 3(2)(-4) - 4(-4)^2

2 * 4 + 3(2)(-4) - 4 * 16

8 - 24 - 64

-80

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Mandy has an IQ of 115. We know that the mean () IQ is 100 with a standard deviation of 15. There are 100 people in Mandy’s Alc

Alex787 [66]

Answer: 16

Step-by-step explanation:

Given : Mean : $\mu=100$

Standard deviation : $\sigma =15$

The value of z-score is given by :-

$z=\dfrac{x-\mu}{\sigma}$

For x= 115

$z=\dfrac{115-100}{15}=1$

The p-value : $P(z>1)=1-P(z$

Now, the number of people smarter than Many is given by :_

$100\times0.1586553=15.86553\approx16$

Hence, there are 16 members smarter than Mandy.

8 0

4 years ago

The following data show the midterm and final exam scores in an English writing class. Student 1 2 3 4 5 6 7 8 9 10 11 12 Midter

tester [92]

Answer:

The co variance of the midterm and final exam scores is 58.76.

Step-by-step explanation:

The formula to compute the sample co variance is:

$Cov(x,y)=\frac{\sum(X-Mean\ of\ X)(Y-Mean\ of\ Y)}{n-1}$

The values are computed in the table below.

Compute the co variance as follows:

$Cov(x,y)=\frac{\sum(X-Mean\ of\ X)(Y-Mean\ of\ Y)}{n-1}\\=\frac{646.33}{12-1}\\ =58.76$

Thus, the co variance of the midterm and final exam scores is 58.76.

7 0

3 years ago

Need help please ?!!!!!

Nutka1998 [239]

A. 28/116
B. 45/182
C. 38/116
D. 18/182

8 0

3 years ago

How do I do this problem

nata0808 [166]

All of the angles in a triangle equal 180° so if the first 2 angles are 60°, combined that equal 120°, leaving 60° left. X= 60°

3 0

3 years ago

What is the volume of the pyramid?

Deffense [45]

Given,

base=6 ft

height=5 ft

Now,

volume of pyramid=1/3×B×h(where B is base area)

=1/3×(6×6)×5

=1/3×36×5

=<em>60 ft cubed</em>

6 0

3 years ago