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Semmy [17]
3 years ago
13

(1 point) A student was asked to find the equation of the tangent plane to the surface z=x2−y3 at the point (x,y)=(5,1). The stu

dent's answer was z=24+2x(x−5)−(3y2)(y−1). (a) At a glance, how do you know this is wrong. What mistakes did the student make? Select all that apply.
Mathematics
1 answer:
Nonamiya [84]3 years ago
5 0

Answer:

Options a and d are the correct ones.

Step-by-step explanation:

The complete question is as follows

A student was asked to find the equation of the tangent plane to the surface z = x^2-y^3 at the point (x,y)=(5,1). The student's answer was  z = 24+2x(x-5)-3y^2(y-1). (a) At a glance, how do you know this is wrong. What mistakes did the student make? Select all that apply.

a) The answer is not a linear function

b) The (x-5) and (y-1) should be x and y

c) the 24 should not be in the answer

d) the partial derivatives were not evaluated at the point

e) all of the above.

Recall that, given a surface of the form z=f(x,y) where f is differentiable, then at a given point (x_0,y_0) we can find the equation of the tangent plane by

z=f(x_0,y_0)+\frac{df}{dx}(x_0,y_0) (x-x_0)+\frac{df}{dy}(x_0,y_0) (y-y_0)

We are given that (x_0,y_0) = (5,1) Note that f(5,1) = 24. Then, c is not true. Also, the formula says that we must have the factors (x-5) and (y-1), since we are evaluating the tangent plane in a neighborhood of that point, hence option b is not true. Since B and C are not true, then E is not true. Note that the given function by the student has a mutiplication of 2x and (x-5) which will give us the function 2x^2-10 which is of degree two. Then, the function given by the student is not a linear function, since linear functions have a degree at most 1. Finally, we must check that d is also true.

REcall that

\frac{df}{dx} = 2x, \frac{df}{dy} = -3y^2

so we see that this coincide with the the terms that multiply the factors (x-5) and (y-1) respectively, which tell us that even though the student was trying to follow the formula, he/she forgot to evaluate the partial derivatives at the given point, hence the option D is also true.

Recall that if we want the tangent plane at the point given, we must evaluate the partial derivatives at x=5 and y=1. Hence, the formula of the tangent plane is

z = 24+10(x-5)-3(y-1)

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Alex787 [66]

Answer:

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Step-by-step explanation:

5 0
3 years ago
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Mrs. Clark has a glass vase with a base shaped like a hexagon, as shown. The vase is 30 cm tall and the hexagon base has an area
Lisa [10]

Answer: The correct option is fourth, i.e., 1935 cm³.

Explanation:

It is given that the vase is 30 cm tall and the hexagon base has an area of 64.5 cm².

The area of a hexagon base is,

A=\frac{3\sqrt{3}} {2}a^2

Where, a is the side length.

The volume of the a hexagon glass is,

V=\frac{3\sqrt{3}} {2}a^2\times h

V=A\times h

Where, A is area of base of hexagon and h is height of the hexagon glass.

V=64.5\times 30

V=1935

Therefore the volume of the glass is 1935 cm³ and the glass can hold 1935 cm³ water. So, fourth option is correct.

4 0
3 years ago
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Twenty words were randomly selected from two textbooks. Each set gives the number of letters in each of the twenty words for tha
Alborosie

Answer:

k = 13The smallest zero or root is x = -10

Step-by-step explanation:

you can write "x^2" to mean "x squared"

f(x) = x^2+3x-10

f(x+5) = (x+5)^2+3(x+5)-10 ... replace every x with x+5

f(x+5) = (x^2+10x+25)+3(x+5)-10

f(x+5) = x^2+10x+25+3x+15-10

f(x+5) = x^2+13x+30

Compare this with x^2+kx+30 and we see that k = 13

Factor and solve the equation below

x^2+13x+30 = 0

(x+10)(x+3) = 0

x+10 = 0 or x+3 = 0

x = -10 or x = -3

The smallest zero is x = -10 as its the left-most value on a number line.

7 0
3 years ago
Triangle XYZ is shown, where n ≥ 5. Triangle X Y Z is shown. The length of side X Y is n + 4, the length of side Y Z is 2 n, and
motikmotik

Answer:

The longest side of the triangle is YZ, the shortest side is ZX, the largest angle is ∠X and the smallest angle is ∠Y.

Step-by-step explanation:

The lengths of the sides of the triangle XYZ are as follows:

XY = n + 4

YZ = 2n

ZX = n - 2

According to the triangle inequality theorem, the sum of two sides of a triangle is always greater than the third side.

Then,

XY < YZ + ZX ⇒ n + 4 < 2n + n - 2 ⇒ n + 4 < 3n - 2 ⇒ 2n > 6 ⇒ n > 3

YZ < XY + ZX ⇒ 2n < n + 4 + n - 2 ⇒ 2n < 2n + 2 ⇒ 0 < 2

ZX < XY + YZ ⇒ n - 2 < n + 4 + 2n ⇒ n - 2 < 3n + 4 ⇒ 2n > -6 ⇒ n > -3

It is provided that <em>n</em> ≥ 5.

Then the sides of the triangle are:

XY = n + 4 ≥ 5 + 4 = 9

YZ = 2n ≥ 2 × 5 = 10

ZX = n - 2 ≥ 5 - 2 = 3

So, the longest side of the triangle is YZ. And the shortest side is ZX.

The largest angle of a triangle is opposite to the longest side.

The angle opposite to YZ would be X. So, the largest angle is ∠X.

The smallest angle of a triangle is opposite to the shortest side.

The angle opposite to ZX would be Y. So, the smallest angle is ∠Y.

Thus, the longest side of the triangle is YZ, the shortest side is ZX, the largest angle is ∠X and the smallest angle is ∠Y.

6 0
3 years ago
Am I correct <br> 2017 -1846= 171<br> 2017-1781= 236<br> 1847-1781=65 yrs difference
Anit [1.1K]
Yes for the first one, yes for the second one, and yes for the third one although your subtraction equation had the wrong year (its not 1847 its 1846) but the answer was right, 65.
5 0
3 years ago
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