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3 years ago

The product of x and 7 is at least 21

Mathematics

2 answers:

Natali [406]3 years ago

8 0

It’ll be 3

7 x 3 = 21

avanturin [10]3 years ago

4 0

3 or greater. You could replace x with any number greater than 3, and your product would be at least 21. I hope this helps :)

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Let us have four distinct collinear points $a,$ $b,$ $c,$ and $d$ on the cartesian plane. the point $c$ is such that $\dfrac{ab}

Deffense [45]

Start with a line segment connecting two points, A and B. $\dfrac{DA}{BA}=3$ means DA is 3 times longer than BA. Clearly, D cannot fall between A and B because that would mean DA is shorter than BA. So there are two possible locations where D can be placed on the line relative to A and B.

But with $\dfrac{DB}{BA}=2$ , or the fact that DB is 2 times longer than BA, we can rule out one of these positions; referring to the attachment, if we place D to the left of A, then DB would be 4 times longer than BA.

Finally, $\dfrac{AB}{CB}=\dfrac12$ , so that CB is 2 times longer than AB. Again we have two possible locations for point C (it cannot fall between A and B), but one of them forces C to occupy the same point as D. However, A, B, C, D are distinct, so C must fall to the left of A.

Now let $d$ be the length of AB. Then the length of CD in terms of $d$ is $4d$ . We have the coordinates of C and D, and the distance between them is $\sqrt{(4-0)^2+(0-4)^2}=4\sqrt2$ . So

$4d=4\sqrt2\implies d=\sqrt2$

The slope of the line through C and D is

$\dfrac{0-4}{4-0}=-1$

and so the equation of the line through these points is

$y-4=-(x-0)\implies x+y=4$

So the coordinates of A are $(x,y)=(x,4-x)$ . The distance between C and A is $d=\sqrt2$ , so we have

$\sqrt{(x-0)^2+(4-x-4)^2}=\sqrt{2x^2}=|x|\sqrt2=\sqrt2\implies|x|=1$

Since A falls to the right of C (in the $x,y$ plane, not just in the sketch), we know to take the positive value $x=1$ . Then the $y$ coordinate is $y=4-1=3$ .

All this to say that A is the point (1, 3), so

$2x+y=2+3=5$

5 0

3 years ago

How do I do this I really don't understand anything here

Lera25 [3.4K]

The red arrows show that the lines are parallel, but using the stuff given you can make an equation.
its hard to explain without drawing but starting from the 60 if you can make a Z you will get alternate angles and that mean that the given equation MUST be equal to 60. So,

8x-4=60

8x=60+4

8x=64

x=64/8

x=8 (is your answer)

hope you understand

8 0

3 years ago

Calculate the slope of the line.<br> Plz help

Doss [256]

Answer:

y = -3

Step-by-step explanation:

you take y

y = -3 badaboom

5 0

3 years ago

Read 2 more answers

How do you do the area and how to do it to the nearest tenth

lord [1]

You just put I line in the middle and you times high times base the do the other one then add your answers up that should be your finely answer

6 0

3 years ago

all unicorns on rainbow island are either green or yellow. every time the clock strikes midnight the unicorns change their color

Oksi-84 [34.3K]

77 unicorns, because yesterday the ratio was 6:5 and today it is 3:4. If you add the numbers for both ratios together, you get 11 and 7. Finding the LCM of these two gives 77 (because 7 and 11 are both prime).

You find the LCM of the sums because when you find values based on ratios, you divide value by the sum of the ratio.

e.g. I have 100 fruits. The ratio of apples to oranges is 2:3. How many apples are there?

To solve this you'd add 2 and 3 (5), divide 100 by 5 (20), multiply that by 2 (40) because that's the ratio of apples to oranges.

In this case, you do the reverse. So If I have 77 unicorns, then yesterday there were (77/11 = 7, 7*6= 42, 7*5= 35) 42 green unicorns and 35 yellow. The sum of 42 and 35 is 77. If you do this process with the other ratio you'll get similar results as well.

6 0

3 years ago