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3 years ago

REVERSE PROPORTION

Mathematics

1 answer:

muminat3 years ago

5 0

9514 1404 393

Answer:

33.3%

Step-by-step explanation:

The selling price of £42 is (1 +40%) times the total purchase price.

1.40 × purchase price = £42

purchase price = £42/1.40 = £30

The total profit is 40% of this, so is ...

£30 × 40% = £12

The purchase price of the skirt is ...

total cost - glove cost = skirt cost = £30 -3 = £27

The profit on the skirt is ...

total profit - glove profit = skirt profit = £12 -100% × £3 = £9

Then the percentage profit on the skirt is ...

skirt profit % = skirt profit / skirt cost × 100% = £9/£27 × 100% = 33.3%

The percentage profit on the cost of the skirt was 33.3%.

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Let f(x) = 1/x^2 (a) Use the definition of the derivatve to find f'(x). (b) Find the equation of the tangent line at x=2

Verdich [7]

Answer:

(a) $f'(x)=-\frac{2}{x^3}$

(b) $y=-0.25x+0.75$

Step-by-step explanation:

The given function is

$f(x)=\frac{1}{x^2}$ .... (1)

According to the first principle of the derivative,

$f'(x)=lim_{h\rightarrow 0}\frac{f(x+h)-f(x)}{h}$

$f'(x)=lim_{h\rightarrow 0}\frac{\frac{1}{(x+h)^2}-\frac{1}{x^2}}{h}$

$f'(x)=lim_{h\rightarrow 0}\frac{\frac{x^2-(x+h)^2}{x^2(x+h)^2}}{h}$

$f'(x)=lim_{h\rightarrow 0}\frac{x^2-x^2-2xh-h^2}{hx^2(x+h)^2}$

$f'(x)=lim_{h\rightarrow 0}\frac{-2xh-h^2}{hx^2(x+h)^2}$

$f'(x)=lim_{h\rightarrow 0}\frac{-h(2x+h)}{hx^2(x+h)^2}$

Cancel out common factors.

$f'(x)=lim_{h\rightarrow 0}\frac{-(2x+h)}{x^2(x+h)^2}$

By applying limit, we get

$f'(x)=\frac{-(2x+0)}{x^2(x+0)^2}$

$f'(x)=\frac{-2x)}{x^4}$

$f'(x)=\frac{-2)}{x^3}$ .... (2)

Therefore $f'(x)=-\frac{2}{x^3}$ .

(b)

Put x=2, to find the y-coordinate of point of tangency.

$f(x)=\frac{1}{2^2}=\frac{1}{4}=0.25$

The coordinates of point of tangency are (2,0.25).

The slope of tangent at x=2 is

$m=(\frac{dy}{dx})_{x=2}=f'(x)_{x=2}$

Substitute x=2 in equation 2.

$f'(2)=\frac{-2}{(2)^3}=\frac{-2}{8}=\frac{-1}{4}=-0.25$

The slope of the tangent line at x=2 is -0.25.

The slope of tangent is -0.25 and the tangent passes through the point (2,0.25).

Using point slope form the equation of tangent is

$y-y_1=m(x-x_1)$

$y-0.25=-0.25(x-2)$

$y-0.25=-0.25x+0.5$

$y=-0.25x+0.5+0.25$

$y=-0.25x+0.75$

Therefore the equation of the tangent line at x=2 is y=-0.25x+0.75.

5 0

3 years ago

What system shows the correct numbers to multiply by the coefficients in order to eliminate y from the first two

Ann [662]

Answer:

3 (5x+2y = 0)

2 (2x – 3y = -19)

Step-by-step explanation:

5x+2y=0 (1)

2x-3y=-19 (2)

To eliminate y from the first two equation when applying the linear combination method

We will multiply y Equation (1) and (2) with 3 and 2 respectively so that the coefficients of y in the two equations +6 and -6 respectively

3(5x+2y=0)

2(2x-3y=-19)

We have,

15x+6y=0 (3)

4x-6y= -38 (4)

Add Equation (3) and (4)

19x=-38

x= -2

Substitute x= -2 into (1)

5x+2y=0

5(-2)+2y=0

-10+2y=0

-10= -2y

y=-10/-2

y=5, x=-2

3 0

3 years ago

What is <br> (2ab-a+2) - (-ab-2)

Greeley [361]

Step-by-step explanation:

iknow but its hard to expalin

8 0

2 years ago

A die is rolled 20 times. given that three of the rolls came up 1, five came up 2, four came up 3, two came up 4, three came up

Serjik [45]

Solution:

Number of times a die is rolled = 20

1 - 3=A

2 - 5=B

3 - 4=C

4 - 2=D

5 - 3=E

6 - 3=F

Total number of arrangements of outcomes , when a dice is rolled 20 times given that 1 appear 3 times, 2 appears 5 times, 3 appear 4 times, 4 appear 2 times , 5 appear three times, and 6 appear 3 times

= Arrangement of 6 numbers (A,B,C,D,E,F) in 6! ways and then arranging outcomes

= 6! × [ 3! × 5! × 4!×2!×3!×3!]

= 720 × 6×120×24×72→→[Keep in Mind →n!= n (n-1)(n-2)(n-3)........1]

= 895795200 Ways

8 0

3 years ago

help PLEASEE! Might post a lot of these sorry

ExtremeBDS [4]

Answer:

A = 189 sq units

Step-by-step explanation:

You can cut the shape up into pieces. See image. There are two rectangles and a triangle. Some sides are given:

rectangle: 16 × 8

sm rectangle: 3 × 4

Some sides you have to add to find (the height of the whole entire thing: 16+4+4)

Some lengths you have to subtract to find (height of the triangle: 24 - 10).

Area of a rectangle:

length × width OR

base × height

Area of a triangle:

1/2 • b • h

Add up all three areas. See image.

4 0

2 years ago

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