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2 years ago

7)) Brainliest and 10+ points!

Mathematics

2 answers:

strojnjashka [21]2 years ago

4 0

Divide by 2, then subtract 4

lara [203]2 years ago

3 0

Answer:

Divide by 2

Then subtract 4

Step-by-step explanation:

Let y = 2(x+4)

Exchange x and y

x = 2(y+4)

We want to solve for y

Divide each side by 2

x/2 = y+4

Then subtract 4 from each side

x/2 -4 =y

The inverse is x/2 -4

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you go to the market to buy fruit.two apples and one banana cost $5. if you buy two apples and three bananas the cost is$7.how m

marissa [1.9K]

Answer:

An apple costs $2 and a banana costs $1.

Step-by-step explanation:

x = cost of 1 apple and y = cost of 1 banana. So:-

2x + y = 5

2x + 3y = 7

Subtract the first equation from the second. We get:-

2y = 2

y = 1

and since 2x + y = 5, 2 x + 1 = 5 and

x = $2.

5 0

2 years ago

PLEASE HELP ASAP In this task, you will practice finding the area under a nonlinear function by using rectangles. You will use g

mrs_skeptik [129]

Answer:

a) $1280 u^{2}$

b) $1320 u^{2}$

c) $\frac{4000}{3} u^{2}$

Step-by-step explanation:

In order to solve this problem we must start by sketching the graph of the function. This will help us visualize the problem better. (See attached picture)

You can sketch the graph of the function by plotting as many points as you can from x=0 to x=20 or by finding the vertex form of the quadratic equation by completing the square. You can also do so by using a graphing device, you decide which method suits better for you.

So we are interested in finding the area under the curve, so we divide it into 5 rectangles taking a right hand approximation. This is, the right upper corner of each rectangle will touch the graph. (see attached picture).

In order to figure the width of each rectangle we can use the following formula:

$\Delta x=\frac{b-a}{n}$

in this case a=0, b=20 and n=5 so we get:

$\Delta x=\frac{20-0}{5}=\frac{20}{5}=4$

so each rectangle must have a width of 4 units.

We can now calculate the hight of each rectangle. So we figure the y-value of each corner of the rectangles. We get the following heights:

h1=64

h2=96

h3=96

h4= 64

h5=0

so now we can use the following formula to find the area under the graph. Basically what the formula does is add the areas of the rectangles:

$A=\sum^{n}_{i=1} f(x_{i}) \Delta x$

which can be rewritten as:

$A=\Delta x \sum^{n}_{i=1} f(x_{i})$

So we go ahead and solve it:

$A=(4)(64+96+96+64+0)$

so:

$A= 1280 u^{2}$

B) The same procedure is used to solve part B, just that this time we divide the area in 10 rectangles.

In order to figure the width of each rectangle we can use the following formula:

$\Delta x=\frac{b-a}{n}$

in this case a=0, b=20 and n=10 so we get:

$\Delta x=\frac{20-0}{10}=\frac{20}{10}=2$

so each rectangle must have a width of 2 units.

We can now calculate the hight of each rectangle. So we figure the y-value of each corner of the rectangles. We get the following heights:

h1=36

h2=64

h3=84

h4= 96

h5=100

h6=96

h7=84

h8=64

h9=36

h10=0

so now we can use the following formula to find the area under the graph. Basically what the formula does is add the areas of the rectangles:

$A=\sum^{n}_{i=1} f(x_{i}) \Delta x$

which can be rewritten as:

$A=\Delta x \sum^{n}_{i=1} f(x_{i})$

So we go ahead and solve it:

$A=(2)(36+64+84+96+100+96+84+64+36+0)$

so:

$A= 1320 u^{2}$

In order to find part c, we calculate the area by using limits, the limit will look like this:

$\lim_{n \to \infty} \sum^{n}_{i=1} f(x^{*}_{i}) \Delta x$

so we start by finding the change of x so we get:

$\Delta x =\frac{b-a}{n}$

$\Delta x =\frac{20-0}{n}$

$\Delta x =\frac{20}{n}$

next we find $x^{*}_{i}$

$x^{*}_{i}=a+\Delta x i$

so:

$x^{*}_{i}=0+\frac{20}{n} i=\frac{20}{n} i$

and we find $f(x^{*}_{i})$

$f(x^{*}_{i})=f(\frac{20}{n} i)=-(\frac{20}{n} i)^{2}+20(\frac{20}{n} i)$

cand we do some algebra to simplify it.

$f(x^{*}_{i})=-\frac{400}{n^{2}}i^{2}+\frac{400}{n}i$

we do some factorization:

$f(x^{*}_{i})=-\frac{400}{n}(\frac{i^{2}}{n}-i)$

and plug it into our formula:

$\lim_{n \to \infty} \sum^{n}_{i=1}-\frac{400}{n}(\frac{i^{2}}{n}-i) (\frac{20}{n})$

And simplify:

$\lim_{n \to \infty} \sum^{n}_{i=1}-\frac{8000}{n^{2}}(\frac{i^{2}}{n}-i)$

$\lim_{n \to \infty} -\frac{8000}{n^{2}} \sum^{n}_{i=1}(\frac{i^{2}}{n}-i)$

And now we use summation formulas:

$\lim_{n \to \infty} -\frac{8000}{n^{2}} (\frac{n(n+1)(2n+1)}{6n}-\frac{n(n+1)}{2})$

$\lim_{n \to \infty} -\frac{8000}{n^{2}} (\frac{2n^{2}+3n+1}{6}-\frac{n^{2}}{2}-\frac{n}{2})$

and simplify:

$\lim_{n \to \infty} -\frac{8000}{n^{2}} (-\frac{n^{2}}{6}+\frac{1}{6})$

$\lim_{n \to \infty} \frac{4000}{3}+\frac{4000}{3n^{2}}$

and solve the limit

$\frac{4000}{3}u^{2}$

4 0

2 years ago

I need help! do i subtract the 45-64? or add!?

Len [333]

Answer:

19°

Step-by-step explanation:

180-64=116

116+45=161

180-161=19

4 0

1 year ago

Read 2 more answers

An airplane needs to head due north, but there is a wind blowing from the northeast at 50 km/hr. The plane flies at an airspeed

laiz [17]

Answer: $\theta =2.415^{\circ}$

Step-by-step explanation:

Using vector method to solve it

Resultant can be given by

$R^2=700^2+40^2+2\times 700\times 40cos135$

$R^2=450,408$

R=671.12 Km/hr

The angle made by resultant with 700 km/hr is $\theta$

using sine rule

$\frac{40}{sin\theat }=\frac{R}{sin45}$

$sin\theta =0.0421509$

$\theta =2.415^{\circ}$

8 0

2 years ago

What are the dimensions of a rectangle with an area of 304 and a perimeter of 70?

Hitman42 [59]

Area = 304 cm^2
perimeter = 70
perimeter = 2(l+w)
70 = 2(l+w)
70/2 = l+w
35 = l+w
Now suppose the length would be = x
width would be= 35-x
NOW Area = l*w
304 = x * (35-x)
304 = 35x -x^2
x^2-35x+304 = 0
use quadratic formula to solve next ok
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5 0

2 years ago