Advertisements
Advertisements
प्रश्न
Find the value of : x3 + 2x2 – 3x + 21, if x = 1 + 2i
उत्तर
x = 1 + 2i
∴ x – 1 = 2i
∴ (x – 1)2 = 4i2
∴ x2 – 2x + 1 = – 4 ...[∵ i2 = – 1]
∴ x2 – 2x + 5 = 0 ...(i)
x + 4
∵ `x^2 – 2x + 5")"overline(x^3 + 2x^2 - 3x + 21)"`
x3 – 2x2 + 5x
– + –
4x2 – 8x + 21
4x2 – 8x + 20
– + –
1
∴ x3 + 2x2 – 3x + 21
= (x2 – 2x + 5)(x + 4) + 1
= 0.(x + 4) + 1 ...[From (i)]
= 0 + 1
∴ x3 + 2x2 – 3x + 21 = 1
APPEARS IN
संबंधित प्रश्न
Express the following expression in the form of a + ib.
`((3 + sqrt5)(3 - isqrt5))/((sqrt3 + sqrt2i)-(sqrt3 - isqrt2))`
Find the value of i + i2 + i3 + i4
Find the value of: 2x3 – 11x2 + 44x + 27, if x = `25/(3 - 4"i")`
Write the conjugates of the following complex number:
3 – i
If (a + ib) = `(1 + "i")/(1 - "i")`, then prove that (a2 + b2) = 1
Show that `((sqrt(7) + "i"sqrt(3))/(sqrt(7) - "i"sqrt(3)) + (sqrt(7) - "i"sqrt(3))/(sqrt(7) + "i"sqrt(3)))` is real
Find the value of x and y which satisfy the following equation (x, y∈R).
(x + 2y) + (2x − 3y)i + 4i = 5
Find the value of x and y which satisfy the following equation (x, y∈R).
If x + 2i + 15i6y = 7x + i3 (y + 4), find x + y
Solve the following equation for x, y ∈ R:
2x + i9y (2 + i) = xi7 + 10i16
Answer the following:
Find the value of x4 + 9x3 + 35x2 − x + 164, if x = −5 + 4i
Answer the following:
Show that `(1 - 2"i")/(3 - 4"i") + (1 + 2"i")/(3 + 4"i")` is real
The equation |z + 1 – i| = |z – 1 + i| represents a ______.
The sum of the series i + i2 + i3 + ... upto 1000 terms is ______.
State True or False for the following:
For any complex number z the minimum value of |z| + |z – 1| is 1.
The value of `(z + 3)(barz + 3)` is equivalent to ______.
If z1, z2, z3 are complex numbers such that |z1| = |z2| = |z3| = `|1/z_1 + 1/z_2 + 1/z_3|` = 1, then |z1 + z2 + z3| is ______.
Find the value of `(i^592+i^590+i^588+i^586+i^584)/(i^582+i^580+i^578+i^576+i^574)`
Simplify the following and express in the form a + ib.
`(3i^5 + 2i^7 + i^9) / (i^6 + 2i^8 + 3i^18)`
Find the value of `sqrt(-3) xx sqrt(-6)`
