Câu 1: Trong các mệnh đề sau, mệnh đề nào là không đúng ?

A. Nếu a // b và (α) vuông góc a thì (α) vuông góc với b

B. Nếu (α) // (β) và a vuông góc với (α) thì a vuông góc với (β)

C. Nếu a và b là hai đường thẳng phân biệt và a vuông góc (α), b vuông góc với (α) thì a // b

D. Nếu a // (α) và b vuông góc a thì b vuông góc (α)

Answer: -78 / 35

Step-by-step explanation:

Given

 2/5 + 3/7 + (-6/5) + (-13/7)

Combine terms that have the same denominator

= 2/5 + (-6/5) + 3/7 + (-13/7)

= -4/5 - 10/7

Convert denominator by Least Common Multiple (LCM)

= (-4 × 7) / (5 × 7) - (10 × 5) / (7 × 5)

= -28/35 - 50/35

= -78 / 35

Hope this helps!! :)

Please let me know if you have any questions

Answer:

[tex] \frac{2}{5} + \frac{3}{7} + ( - \frac{6}{5} ) + ( - \frac{13}{7} ) \\ \frac{2}{5} + \frac{3}{7} - \frac{6}{5} - \frac{13}{7} \\ ( \frac{2}{5} - \frac{6}{5} ) + ( \frac{3}{7} - \frac{13}{7} ) \\ \frac{2 - 6}{5} + \frac{3 - 13}{7} \\ \frac{ - 4}{5} + \frac{ - 10}{7} \\ \frac{ - 4}{5} - \frac{10}{7} \\ \frac{ - 28 - 50}{35} \\ \frac{ - 78}{35} \\ - \frac{78}{35} [/tex]

Answer:

(x-5)(x+2)(x+4)

Step-by-step explanation:

I just did It

Answer:

Oxygen; 34.01°C

Step-by-step explanation:

The oxygen freezes first as it has a higher (warmer) freezing point. For both to freeze, the temperature must drop a further 34.01°C as:

-218.79 - (-252.8)

= 252.8 - 218.79

= 34.01

Answer:

[tex]c=-2[/tex]

Step-by-step explanation:

We are given the function:

[tex]f(x) = -2c + cx - x^2[/tex]

And that:

[tex]\displaystyle f^{-1} (5) = -1[/tex]

And we want to determine the value of c.

Recall that by definition of inverse functions:

[tex]\displaystyle \text{If } f(a) = b, \text{ then } f^{-1}(b) = a[/tex]

So, since f⁻¹(5) = -1, then f(-1) = 5.

Substitute:

[tex]f(-1) = 5 = -2c + c(-1) - (-1)^2[/tex]

Simplify:

[tex]5 = -2c - c - (1)[/tex]

Combine like terms:

[tex]6 = -3c[/tex]

And divide. Hence:

[tex]c = -2[/tex]

In conclusion, the value of c is -2.

Answer:

900°

Step-by-step explanation:

The sum of the interior angles of a polygon is

sum = 180° (n - 2) ← n is the number of sides

Here n = 7 , then

sum = 180° × 5 = 900°

Answer:

B

Step-by-step explanation:

here we use trigonometric ratio involving soh,cah,toa

Answer: x = -3

[tex]2x+6=0\\\\2x=-6\\\\x=\frac{-6}{2} =-3[/tex]

Answer:

x= -3

Step-by-step explanation:

Solve the equation:

2x +6 = 0

We have isolate 'x'.

First subtract 6 from both sides

2x = 0-6

2x = -6

Divide each side by 2

x = -6/2

x = -3

Answer:

[tex]we \: know \: that \: commutative \: prop \\ = x + y = y + x \\ then \\ 4xy + 0 = 0 + 4xy \\ thank \: you[/tex]

Answer:

0.04

Step-by-step explanation:

2 / 50 is the same as 1 / 25.

1 / 25 = 0.04

Answer:

0.04

Step-by-step explanation:

Answer:

-13 1/2 < -6/8

Step-by-step explanation:

*Any negative in either the numerator or denominator will make the entire fraction negative.

1/2  = .5

-13 1/2 = -13.5

-6/8 = -3/4

-3/4 = -0.75

-6/8 = -0.75

-13 1/2 = -13.5

Which means:

-13 1/2 < -6/8

Hope this helped.

Answer:

[tex] < [/tex]

Step-by-step explanation:

[tex] \frac{6}{8} [/tex]

Is close to 0 (to positive) you can use a time line to determine which is a correct answer

Answer:

x = 0

Step-by-step explanation:

-2(2 − 2x) = 4 − 8(1 − x)

Apply the distributive property:

−2(2 − 2x) = 4 − 8(1 − x)

(−2)(2) + (−2)(−2x) = 4 + (−8)(1) + (−8)(−x)

−4 + 4x = 4 + (−8) + 8x

Combine like terms:

4x − 4 = (8x) + (4+−8)

4x − 4 = 8x + (−4)

4x − 4 = 8x − 4

Subtract 8x from both sides:

4x − 4 − 8x = 8x − 4 − 8x

−4x − 4 = −4

Add 4 to both sides:

−4x − 4 + 4= −4 + 4

−4x = 0

Divide both sides by -4:

-4x/-4 = 0/-4

x = 0

Answer: 0

Step-by-step explanation:

Answer:

1861÷1250

Step-by-step explanation:

This is the simplified version

Answer:

x=1

Step-by-step explanation:

3x+9 = 12

Subtract 9 from each side

3x+9-9=12-9

3x = 3

Divide by 3

3x/3 = 3/3

x=1

Hi there!  

»»————-　★　————-««

I believe your answer is:  

[tex]x = 1[/tex]

»»————-　★　————-««  

Here’s why:  

⸻⸻⸻⸻

[tex]\boxed{\text{Calculating the answer...}}\\\\3x + 9 = 12\\-------------\\\rightarrow 3x + 9 - 9 = 12 - 9\\\\\rightarrow 3x = 3\\\\\rightarrow \frac{3x=3}{3}\\\\\rightarrow \boxed{x=1}[/tex]

⸻⸻⸻⸻

»»————-　★　————-««  

Hope this helps you. I apologize if it’s incorrect.  

Answer:

37.5%

Step-by-step explanation:

150/450 = .375 = 37.5%

The percentage is 150 grams out of 400 grams will be 37.5%.

The quantity of anything is stated as though it were a fraction of a hundred. A quarter of 100 can be used to express the ratio. Per 100 is what the term percent signifies. The symbol '%' is used to symbolize it.

The percentage is given as,

Percentage (P) = [Initial value - Final value] / Initial value x 100

It is given that the difference between the initial and final value is 15 grams and the initial value is 400 grams.

Then the percentage is 150 grams out of 400 grams will be

P = (150 / 400) x 100

P = 0.375 x 100

P = 37.5%

Thus, the percentage is 150 grams out of 400 grams will be 37.5%.

More about the percentage link is given below.

https://brainly.com/question/8011401

#SPJ2

Answer:

c

Step-by-step explanation:

come on ! you can literally see that in the chart.

how many parts of the gray 3/8 are covered by the gray 1/4 ?

2 parts = 2/8 are clearly covered by 1/4.

2/8 is what part of 3/8 ?

it is the same question as "2 is what part of 3" ?

is 2 a quarter (1/4) of 3 ? no, 1/4×3 = 3/4 and not 2.

is 2 one third (1/3) of 3 ? no, 1/3 of 3 = 1/3×3 = 1 and not 2.

is 2 two thirds (2/3) of 3 ? ah, 2/3 × 3 = 2. that is correct !

is 2 three quarters (3/4) of 3 ? no, 3/4×3 = 9/4 and not 2.

once you have the same denominator, you can easily compare the numerators and ignore the denominators for such problems.

Answer:

B. 7y - 15

Step-by-step explanation:

Simplifying

10y + -3(y + 5) = 0

Reorder the terms:

10y + -3(5 + y) = 0

10y + (5 * -3 + y * -3) = 0

10y + (-15 + -3y) = 0

Reorder the terms:

-15 + 10y + -3y = 0

Combine like terms: 10y + -3y = 7y

-15 + 7y = 0

Solving

-15 + 7y = 0

Solving for variable 'y'.

Move all terms containing y to the left, all other terms to the right.

Add '15' to each side of the equation.

-15 + 15 + 7y = 0 + 15

Combine like terms: -15 + 15 = 0

0 + 7y = 0 + 15

7y = 0 + 15

Combine like terms: 0 + 15 = 15

7y = 15

Divide each side by '7'.

y = 2.142857143

Simplifying

y = 2.142857143

Answer:

b. 7y-15

Step-by-step explanation:

First, write out the expression

1. [tex]10y-3(y+5)[/tex]

To simplify the expression distribute the -3 to the terms within the paratheses.

2. [tex]10y-3y-15[/tex]

Then, combine like terms to simplify further. Since 10y and -3y are like terms they can be subtracted

3. [tex]7y-15[/tex]

This means that B is the correct answer.

Answer:

22 m/s

Step-by-step explanation:

Take the distance and divide by the time

1210 m/55s

22 m/s

Answer:

Step-by-step explanation:

[tex]speed = \frac{distantce}{time} \\ = \frac{1210m}{55s} \\ = 22m {s}^{ - 1} [/tex]

Answer:

The measure of angle JKM is:

JKL - MKL = JKM

⇒80°-25°=55°

so measure of angle JKM is 55°

Step-by-step explanation:

Answer: [tex]a=\sqrt{60}[/tex]

Step-by-step explanation:

To solve for a, we want to use Pythagorean Theorem as provided int eh problem. a and 2 are the legs while 8 is the hypotenuse.

[tex]a^2+2^2=8^2[/tex]           [exponent]

[tex]a^2+4=64[/tex]            [subtract both sides by 4]

[tex]a^2=60[/tex]                  [square root both sides]

[tex]a=\sqrt{60}[/tex]

Now we know that [tex]a=\sqrt{60}[/tex].

Answer:

see explanation

Step-by-step explanation:

(1)

x - (9x - 10) + 11 = 12x + 3(- 2x + [tex]\frac{1}{3}[/tex] ) ← distribute parenthesis on both sides

x - 9x + 10 + 11 = 12x - 6x + 1 ← collect like terms on both sides

- 8x + 21 = 6x + 1 ( subtract 6x from both sides )

- 14x + 21 = 1 ( subtract 21 from both sides )

- 14x = - 20 ( divide both sides by - 14 )

x = [tex]\frac{-20}{-14}[/tex] = [tex]\frac{10}{7}[/tex]

(3)

- 4x - 2(8x + 1) = - (- 2x - 10) ← distribute parenthesis on both sides

- 4x - 16x - 2 = 2x + 10

- 20x - 2 = 2x + 10 ( subtract 2x from both sides )

- 22x - 2 = 10 ( add 2 to both sides )

- 22x = 12 ( divide both sides by - 22 )

x = [tex]\frac{12}{-22}[/tex] = - [tex]\frac{6}{11}[/tex]

(7)

8(2x + 9) = 56 ( divide both sides by 8 )

2x + 9 = 7 ( subtract 9 from both sides )

2x = - 2 ( divide both sides by 2 )

x = - 1

Answer:

(I'll leave cm out to save space and time in the answer)

the perimeter is 500, there are 5 sides. so on average a side will be 100.

that's already the important key idea.

it's indeed 100 for the third side, the second will be 10 less, the fourth 10 more (making the 2and and the 4th side 200 in sum, and therefore still 100 on average).

repeat this for the 1. and 5. side and we get:

80

90

100

110

120

Answer:

MO, NO, MN

Step-by-step explanation:

First, we can identify this triangle as a right triangle, as given by the square next to the O. Next, we know that a right angle is equal to 90 degrees, and the sum of the angles of a triangle is equal to 180 degrees.

Therefore,

∠M + ∠O + ∠N (the angles of the triangle) = 180

49 + 90 + ∠N = 180

139 + ∠N = 180

subtract both sides by 139 to isolate the variable

∠N = 41

Therefore, ∠N is 41 degrees.

In a triangle, given the angles, we know that the side opposite the smallest angle is the side with the smallest length and so on.

Our angle lengths are

41, 49, and 90 degrees in order.

Therefore, the side opposite the largest angle (90 degrees, or ∠O) is the longest side. This is MN. Similarly, ∠N is the smallest angle, and the side opposite of that (MO) is the shortest side. This leaves NO to be in the middle

Answer:

a + b =1

Step-by-step explanation:

Write the given quadratic as x^2 – 1x – 90 = 0.  This factors into

(x - 10)(x + 9) = 0, and so the roots/solutions are {-9, 10}.

If we call -9 "a" and 10 "b," then the sum a + b is -9 + 10, or a + b =1.

Answer:

D

Step-by-step explanation:

The quotient of n and 8 is [tex]\frac{n}{8}[/tex] and 13 more than this is

[tex]\frac{n}{8}[/tex] + 13 → D

Answer:

110.5 cubic inches

Step-by-step explanation:

Base is parallelogram, so area is

A = 4.7×5 = 23.5

Height(h) is 4.7, so volume is,

V = A×h

= 23.5×4.7

= 110.45 ≈ 110.5

Answered by GAUTHMATH

Answer:

Step-by-step explanation:

757 minutes = 12 hours 37 minutes