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4 years ago

Calcule 2x² - x + 3 para os seguintes valores de x:

Mathematics

1 answer:

sattari [20]4 years ago

7 0

B is the correct answer

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A motorboat, that has speed of 10 km/hour in still water, left a pier traveling against the current of the river. Forty-five min

Nutka1998 [239]

Answer:

2 km/h

Step-by-step explanation:

distance = speed × time
time = distance/speed

Let c represent the speed of the current of the river in km/h. Then the speed of the boat upstream is (10-c). In 3/4 hour, the distance traveled upstream is ...

... distance upstream = (3/4)·(10 -c)

The time taken to travel the same distance downstream is given as 3 hours. The speed in that direction is c, so we have ...

... 3 = distance upstream/c = (3/4)(10 -c)/c

Multiplying this equation by 4c, we get ...

... 12c = 3(10 -c)

... 15c = 30 . . . . . . . . add 3c

... c = 2 . . . . . . . . . . . divide by 15

The speed of the river current is 2 km/h.

7 0

4 years ago

Two vertical poles of lengths 11 ft and 14 ft stand 16 ft apart. A cable reaches from the top of one pole to some point on the g

Alex17521 [72]

We are given

total length of cable is 30 feet

and this cable is on hypotenuse sides of the triangles

so, we can draw triangle as

Let's assume those hypotenuse as 'a' and 'b'

so, we will have

$a+b=30$

now, we can find 'a' and 'b' from triangle

Smaller triangle:

$a=\sqrt{x^2+11^2}$

Larger triangle:

$b=\sqrt{(16-x)^2+14^2}$

we know that

$a+b=30$

so, we can plug this value

and we get

$\sqrt{x^2+11^2}+\sqrt{(16-x)^2+14^2} =30$

now, we can solve for x

$\left(\sqrt{x^2+11^2}\right)^2=\left(30-\sqrt{\left(16-x\right)^2+14^2}\right)^2$

$32x-1231=-60\sqrt{x^2-32x+452}$

$1024x^2-78784x+1515361=3600x^2-115200x+1627200$

now, we can use quadratic formula

we get

$x=\frac{-\sqrt{36416^2-1152389056}+36416}{5152},\:x=\frac{\sqrt{36416^2-1152389056}+36416}{5152}$

$x=4.510,x=9.627$

so,

The point should be located 4.510 feet , 9.627 feet from the smaller pole to use 30 feet cable............Answer

6 0

3 years ago

Unit fraction of 12/84

maks197457 [2]

I am thinking its 1/7

4 0

3 years ago

Read 2 more answers

What is the domain of the function on the graph?

MA_775_DIABLO [31]

Answer:

Option 2

Step-by-step explanation:

4 0

3 years ago

Examine the following sequence 1, 4, 9, 16, 25…. Why is 36 the next number in the sequence? Because the pattern is:

Alexxandr [17]

Its a sequence of squares ..... sixthe term = 6^2 (36)

6 0

3 years ago