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inn [45]
3 years ago
14

Systems of 3 equations by using a combination of both substitution and elimination

Mathematics
1 answer:
LiRa [457]3 years ago
6 0
X-2y+z=3
2x+y-2z=31
-x+2y+3z=-23
multiply the first equation by -2 and add the results to the second equation:
x-2y+z=3
+5y-4z=25
-x+2y+3z=-23
multiply the first equation by 1 and the results to the third equation:
 x-2y+z=3
5y-4z=25
4z=-20
solve for z:
4z=-20
z=-5
solve for y:
5y-4z=25,z=-5
5y-(4*-5)=25
5y+20=25
5y+20-20=25-20
5y=5
y=1
solve for x by substituted y and z into the first equation:
x-2y+z=3, y=1, z=-5
x-(2*1)-5=3
x-2-5=3
x-7=3
x-7+7=3+7
x=10
the answer are x=10, y=1, z=-5
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3 0
4 years ago
A group of rowdy teenagers near a wind turbine decide to place a pair of
Marrrta [24]

Answer:

a) Hence the equation of the sinusoidal function that describes the height of the shorts in terms of time is y = 9 + 7* sin(\pi * t / 15 - \pi  / 6)

b) Hence the height of the shorts at exactly t = 10 minutes, to

the nearest tenth of a meter is 5.5 meters

Step-by-step explanation:

a) The wind turbine blade traverses a circular path as it rotates with time (t), whose time variation is given by the following trajectory equation :

x^2 + (y-yc)^2 = R^2 ,

where  

R = (16 m - 2 m)/2 (since diameter = maximum height - minimum height of the pink short)

= 14 m / 2

= 7 m (radius of the circle)

Also, center of the circle will be at (0, 2 + R) i.e (0,9)

So,  is the trajectory path equation to the circle

Let x = 7* cos(w*t + \phi ) & y = 9 + 7* sin(w* t + \phi) be the parametric form of the above circle equation which represent the position of the pink shorts at the tip of the blade at time t  

At t= 10s, y = 16 m so we have,

9 + 7 * sin(10* w + \phi) = 16 ---------------(1)

Also, at t= 25s, y =2 m so we have,

9 + 7* sin(25 * w +\phi) = 2--------------(2)

Solving we have, 10* w + \phi = \pi/2 & 25*w + \phi = 3*pi/2

15* w = \pi\\\\w = \pi/15 & \phi = \pi/2 - 10*\pi/15 = -\pi / 6  

Therefore y = 9 + 7* sin(\pi * t / 15 - \pi  / 6) is the instantaneous height of the pink short at time t ( in seconds)

b) At t= 10minutes = 10 * 60 s = 600s, we have,

y = 9 + 7 * sin(\pi * 600/15 - \pi / 6)\\\\= 9 + 7 * sin(40* \pi - \pi / 6)

= 5.5 meters (pink short will be at 5.5 meters above ground level at t= 10 minutes)

5 0
3 years ago
Indicate the equation of the given line in standard form, in the equation box below.
Illusion [34]

Perpendicular lines have slopes that are negative reciprocals of each other, so the equation of the line in point-slope form is:

y-4=-\frac{5}{2}(x+3)

Rewriting this in standard form,

2y-8=-5(x+3) \\ \\ 2y-8=-5x-15 \\ \\ \boxed{5x+2y=-7}

6 0
3 years ago
a painter can paint 20 windows in one day. If he has to paint 50 pairs of windows how much time will he take to paint
vazorg [7]

Answer:

50*2=100

100/20=5

The answer is 5 days!

5 0
3 years ago
A dogs weighs 7 pounds and triples each year for two years. How much does the dog weigh?
Tanya [424]
Year 1: 7lbs x 3years= 21lbs
Year 2: 21lbs x 3years = 63lbs
5 0
3 years ago
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