मराठी
महाराष्ट्र राज्य शिक्षण मंडळएचएससी विज्ञान (सामान्य) इयत्ता ११ वी

Express the following in the form of a + ib, a, b∈R i = −1. State the values of a and b: (2+i)(3-i)(1+2i) - Mathematics and Statistics

Advertisements
Advertisements

प्रश्न

Express the following in the form of a + ib, a, b∈R i = `sqrt(−1)`. State the values of a and b:

`((2 + "i"))/((3 - "i")(1 + 2"i"))`

बेरीज

उत्तर १

`((2 + "i"))/((3 - "i")(1 + 2"i"))`

`= (2 + "i")/(3 + 6"i" - "i" - 2"i"^2)`

= `(2 + "i")/(3 + 5"i" - 2(-1))`  ...[∵ i2 = – 1]

= `(2 + "i")/(5 + 5"i")`

= `(2 + "i")/(5(1 + "i"))`

= `((2 + "i")(1 - "i"))/(5(1 + "i")(1 - "i"))`

= `(2 - 2"i" + "i" - "i"^2)/(5(1 - "i"^2)`

= `(2 - "i" - (-1))/(5[1 - (-1)]`  ...[∵ i2 = – 1]

= `(3- "i")/10`

∴ `(2 + "i")/((3 - "i")(1 + 2"i")) = 3/10 - 1/10"i"` 

∴ a = `3/10` and b = `(-1)/10`

shaalaa.com

उत्तर २

`((2 + "i"))/((3 - "i")(1 + 2"i"))`

`= (2 + "i")/(3 + 6"i" - "i" - 2"i"^2)`

= `(2 + "i")/(3 + 5"i" - 2(-1))`             ...[∵ i2 = – 1]

= `(2 + "i")/(3 + 5"i" + 2)` 

= `(2 + "i")/(5 + 5"i")`

= `((2 + "i").(5 - 5"i"))/((5 + 5"i").(5 - 5"i"))`

= `(10 - 10"i" + 5"i" - 5"i"^2)/(5^2 - 5"i"^2)`

= `(10 - 10"i" + 5"i" - 5(-1))/(5^2 - 5"i"^2)`              ...[∵ i2 = – 1]

= `(10 - 10"i" + 5"i" + 5)/(5^2 - 5"i"^2)` 

= `(15 - 5"i")/(25 - 25(-1))`  

= `(15 - 5"i")/(25 +25)`  

= `(15 - 5"i")/(50)`  

= `15/50 - (5"i")/50`  

= `3/10 - (1"i")/10` 

∴ write in a + ib form

∴ a = `3/10` and b = `(-1)/10`

shaalaa.com
  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 1: Complex Numbers - Exercise 1.1 [पृष्ठ ६]

APPEARS IN

संबंधित प्रश्‍न

Express the given complex number in the form a + ib: `(5i) (- 3/5 i)`


Evaluate: `[i^18 + (1/i)^25]^3`


Evaluate the following:

\[i^{49} + i^{68} + i^{89} + i^{110}\]


Find the value of the following expression:

i49 + i68 + i89 + i110


Find the value of the following expression:

i5 + i10 + i15


Find the value of the following expression:

\[\frac{i^{592} + i^{590} + i^{588} + i^{586} + i^{584}}{i^{582} + i^{580} + i^{578} + i^{576} + i^{574}}\]


Find the value of the following expression:

(1 + i)6 + (1 − i)3


Express the following complex number in the standard form a + i b:

\[\frac{3 + 2i}{- 2 + i}\]


Express the following complex number in the standard form a + i b:

\[\frac{(1 + i)(1 + \sqrt{3}i)}{1 - i}\] .


Find the real value of x and y, if

\[(x + iy)(2 - 3i) = 4 + i\]


Find the real value of x and y, if

\[\frac{(1 + i)x - 2i}{3 + i} + \frac{(2 - 3i)y + i}{3 - i}\]


Find the smallest positive integer value of m for which \[\frac{(1 + i )^n}{(1 - i )^{n - 2}}\] is a real number.

 

If \[\left( \frac{1 + i}{1 - i} \right)^3 - \left( \frac{1 - i}{1 + i} \right)^3 = x + iy\] find (xy).


If \[\frac{\left( 1 + i \right)^2}{2 - i} = x + iy\]  find x + y.


If z1 is a complex number other than −1 such that \[\left| z_1 \right| = 1\] and \[z_2 = \frac{z_1 - 1}{z_1 + 1}\] then show that the real parts of z2 is zero.


If \[\frac{z - 1}{z + 1}\] is purely imaginary number (\[z \neq - 1\]), find the value of \[\left| z \right|\].


Write (i25)3 in polar form.


Express the following complex in the form r(cos θ + i sin θ):

\[\frac{1 - i}{\cos\frac{\pi}{3} + i\sin\frac{\pi}{3}}\]


If z1 and z2 are two complex numbers such that \[\left| z_1 \right| = \left| z_2 \right|\] and arg(z1) + arg(z2) = \[\pi\] then show that \[z_1 = - \bar{{z_2}}\].


Express \[\sin\frac{\pi}{5} + i\left( 1 - \cos\frac{\pi}{5} \right)\] in polar form.


If \[z = \frac{- 2}{1 + i\sqrt{3}}\],then the value of arg (z) is


If \[z = \left( \frac{1 + i}{1 - i} \right)\] then z4 equals


\[\text { If } z = \frac{1}{(1 - i)(2 + 3i)}, \text { than } \left| z \right| =\]


\[\text { If  }z = 1 - \text { cos }\theta + i \text { sin }\theta, \text { then } \left| z \right| =\]


The argument of \[\frac{1 - i}{1 + i}\] is


A real value of x satisfies the equation  \[\frac{3 - 4ix}{3 + 4ix} = a - ib (a, b \in \mathbb{R}), if a^2 + b^2 =\]


The complex number z which satisfies the condition \[\left| \frac{i + z}{i - z} \right| = 1\] lies on


Simplify : `sqrt(-16) + 3sqrt(-25) + sqrt(-36) - sqrt(-625)`


Find a and b if (a+b) (2 + i) = b + 1 + (10 + 2a)i


Express the following in the form of a + ib, a, b∈R i = `sqrt(−1)`. State the values of a and b:

`(3 + 2"i")/(2 - 5"i") + (3 -2"i")/(2 + 5"i")`


Find the value of `(3 + 2/"i")("i"^6 - "i"^7)(1 + "i"^11)`


Evaluate the following : i93  


If `((1 + "i"sqrt3)/(1 - "i"sqrt3))^"n"` is an integer, then n is ______.


State true or false for the following:

If a complex number coincides with its conjugate, then the number must lie on imaginary axis.


If a = cosθ + isinθ, find the value of `(1 + "a")/(1 - "a")`.


Find the value of `(i^(592) + i^(590) + i^(588) + i^(586) + i^(584))/(i^(582) + i^(580) + i^(578) + i^(576) + i^(574))`


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×