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liubo4ka [24]
3 years ago
8

Solve x2 - 4x - 7 = 0 by completing the square. What are the solutions?

Mathematics
1 answer:
Roman55 [17]3 years ago
5 0

Answer:

x= 2 + √11 or x = 2 −√11

Step-by-step explanation:

I am going to complete the square step-by-step.

x² − 4x − 7=0

Step 1: Add 7 to both sides.

x² − 4x − 7+ 7 = 0 + 7

x² − 4x = 7

Step 2: The coefficient of -4x is -4. Let b = -4.

Then we need to add (b/2)² = 4 to both sides to complete the square.

Add 4 to both sides.

x² − 4x + 4 = 7 + 4

x² − 4x + 4 = 11

Step 3: Factor left side.

(x−2)² = 11

Step 4: Take square root.

x − 2 = ±√11

Step 5: Add 2 to both sides.

x − 2 + 2 = 2 ±√11

x = 2 ±√11

x= 2 + √11 or x = 2 −√11

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classify each angle pair using all the names that apply using the diagram on the left , answering 1 2 3 4 and 5 , explain why.(
vredina [299]

Answer:

  see the attachment

Step-by-step explanation:

1.  Two angles that sum to 90° are <em>complementary</em>, whether they are adjacent or not. Angles LMN and NMP are also <em>adjacent</em>.

2.  Vertical angles created by two distinct lines are <em>never adjacent</em>. The sides of the angles are created by the same lines, and the angles share a vertex, but there is no ray that is a side common to both angles.

3.  Angle GMK is supplementary to angle JMG.

4.  Vertical angles are congruent. See question 2.

5.  See question 1.

6 0
3 years ago
Find the rectangular coordinates of the point with the polar coordinates (3, 3 divided by 2 pi ). (1 point)
kifflom [539]

Answer:

The correct choice is (0,-3)

Step-by-step explanation:

To convert from polar coordinates to rectangular coordinates, we use the parametric equations:

x=r\cos \theta and y=r\sin \theta

The point given to us in polar coordinates is (3,\frac{3}{2}\pi).

where r=3,\theta=\frac{3\pi}{2}

x=3\cos (\frac{3\pi}{2}) and y=3\sin( \frac{3\pi}{2})

x=3(0) and y=3(-1)

x=0 and y=-3

The correct choice is (0,-3)

5 0
3 years ago
A painter charges an initial fee of $50 and $30 for each hour of labor. Write a linear function to determine the total cost. How
il63 [147K]
The initial fee of $50 is essentially the y intercept because this is the value when x = 0 (x is the number of labor-hours). So b = 50.

The slope is m = 30 because each increase of 1 hour leads to the cost bumping up by 30 dollars. In other words, slope = rise/run = (change in cost)/(change in hours) = 30/1

So we plug m = 30 and b = 50 into the y = mx+b formula to get y = 30x+50

Replace y with f(x) to get f(x) = 30x+50

The linear function for the cost is f(x) = 30x+50

Note: Some books may use other letters (instead of x and f(x)), but the idea is still the same

Once you know the cost function, you replace x with 4.5 to find the amount it will cost to have a painter work for 4.5 hours.

f(x) = 30x+50
f(4.5) = 30*4.5+50
f(4.5) = 135+50
f(4.5) = 185

It will cost 185 dollars to have the painter work for 4.5 hours
7 0
3 years ago
Ten more than-one third of a number is sixteen. Which of the following represents the number?
mart [117]
I want to say b. 18
Hope I helped
5 0
2 years ago
Read 2 more answers
Can anyone help me ?
Delvig [45]

Answer:

see below

Step-by-step explanation:

1.

a)

the relation is

y=5x+28

b)

f(x)=5x+28

we can use it because for every value of  x there is just one value, as the definition of function states

c)

f(22)=?\\\\f(22)=5(22)+28\\\\f(22)=110+28\\\\f(22)=138

and

f(?)=128\\\\5x+28=128\\\\5x=128-28\\\\5x=100\\\\x=20

2.

the points are

(-2,2) with

x_1=-2\\\\y_1=2

(1,-3) with

x_2=1\\\\y_2=-3

so the change in y is      y_2-y_1

-3-(2)=-5

and the change in x is   x_2-x_1

1-(-2)=3

so the slope is

\frac{\:Change\:in\:y}{Change\:in\:x} =\frac{-5}{3} =-\frac{5}{3}

and the general formula is

y=ax+b

so with a=-5/3

we plug in point 1

2=-\frac{5}{3} (-2)+b\\\\2=\frac{10}{3} +b\\\\6=10+3b\\\\6-10=3b\\\\-4=3b\\\\-\frac{4}{3}=bso the formula is

y=-\frac{5}{3}x-\frac{4}{3}

expressed as a function is

f(x)=-\frac{5}{3}x-\frac{4}{3}

3.

this is bassically all the work of number 2, so we have

(-2,-5)

x_1=-2\\\\y_1=-5

(4,31)

x_2=4\\\\y_2=31

so the slope will be

the change in y    y_2-y_1

31-(-5)=36

the change in x   x_2-x_1

4-(-2)=6

so the slope will be

\frac{\Delta\:y}{\Delta\:x}=\frac{36}{6} =6                                              (the triangle means change)

so the formula we have

y=mx+b\\\\y=6x+b

we plug some point, let's say 1

-5=6(-2)+b\\\\-5=-12+b\\\\-5+12=b\\\\7=b

so the formula is

y=6x+7

as a function is

f(x)=6x+7

so there you have it

Just as a note, for the next one, put more points :)

7 0
3 years ago
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