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ValentinkaMS [17]
3 years ago
6

Value of complex number i^7+1/i^4​

Mathematics
1 answer:
Vera_Pavlovna [14]3 years ago
7 0

i^7 + \dfrac 1{i^4}\\\\=i^2 \cdot i^2 \cdot i^2  \cdot i + \dfrac 1{i^2 \cdot i^2}\\\\=(-1)(-1)(-1)i + \dfrac 1{(-1)(-1)} ~~~;[ i^2 = -1] \\\\\ = (-1)^3 i+ \dfrac 1{(-1)^2} \\\\=-i+1

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A building casts a 50-foot shadow. Alex is 5 feet tall and casts a 6-foot shadow. Approximately how tall is the building?
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You have to make a proportion. Set it up 5/6 = x/50. Then cross multiply. 5x50=250. 6 x <em>(x)</em> = 6x. 6x=250. 250/6=41.66666. x=41.6666. Round up, and the building is about 42 ft. tall. 
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4 years ago
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The coordinates of AB are A(2,3) and B(8,1) The perpendicular bisected of AB is CD and point C lies on AB the length of CD is 10
lianna [129]

Answer:

The Coordinates of Point C are C(5,2)

The slope of CD is 3

The possible coordinates of point D(a,b) are (6, 5) and (4, -1)

Step-by-step explanation:

According to the Question,

  • Given, The end points of AB are A(2,3) and B(8,1). The perpendicular Bisector of AB is CD, and point C lies on AB. The length of the CD is √10 units.

Now, Let The Coordinates of Point C are C( x , y ) .

  • Thus, C( x , y ) =  \frac{(8+2)}{2} , \frac{(1+3)}{2}

        The Coordinates of Point C are C( x , y ) =  \frac{(10)}{2} , \frac{(4)}{2} ⇒C(5, 2).

  • And, The slope of AB = \frac{(1-3)}{(8-2)} ⇒ \frac{-2}{6} ⇔ \frac{-1}{3} .

       Thus, The slope of CD is \frac{-1}{The slope of AB}  =  \frac{-1}{\frac{-1}{3} }  ⇔  3.

  • Let the coordinate of D be (a, b) then

       ⇒ √{ (b - 2)² +(a - 5)² } = √10

      on squaring both sides we get,

       ⇒ a² - 10a + 25 + b² - 4b + 4 = 10

       ⇒ a² + b² - 10a - 4b = - 19 ⇔⇔ (Equation 1)

  • We Know, the slope of CD = 3

     ⇒Thus,  (b - 2)/(a - 5) = 3

     ⇒ b - 2 = 3a - 15

     ⇒ b = 3a - 13 ⇔⇔ (Equation 2)

  • Putting value of Equation 2 into Equation 1, We get

 ⇒a² + (3a - 13)² - 10a - 4(3a - 13) = - 19

 ⇒a² + 9a² - 78a + 169 - 10a - 12a + 52 = - 19

 ⇒10a² - 100a + 240 = 0

 ⇒a² - 10a + 24 = 0

 ⇒(a - 4)(a - 6) = 0

 ⇒a = 4 or a = 6

Now,

  • When a = 4 , b = 3(4) - 13 ⇒ 12 - 13 ⇒ b = -1
  • When a = 6, b = 3(6) - 13 ⇒ 18 - 13 ⇒ b = 5

Therefore, the possible coordinates of point D(a,b) are (6, 5) and (4, -1).

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julia-pushkina [17]

Answer:

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Step-by-step explanation:

x=0.212121212........                                                         .........1  equation

10x=2.12121212.........                                                       ........2   equation

1 equation - 2 equation

9x=1.91

x=1.91/9

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