(3 + 4i)(1 − 2i)
- Operation
- Multiply z₁ × z₂
- z₁
- 3 + 4i
- z₂
- 1 - 2i
- نتیجہ
- 11 − 2i
- Real part
- 11
- Imaginary part
- -2
جانچ کا ماخذ: 3 − 6i + 4i − 8i² = 11 − 2i (hand calculation; Python (3+4j)*(1-2j))
Add, subtract, multiply and divide complex numbers, raise them to powers, find nth roots, and convert a + bi to polar form, with an Argand diagram.
تازہ کاری جانچی گئی مثالیں: 7
z₁ × z₂ = 11 − 2i, which is 11.18034 ∠ −10.304846° in polar form.
A complex number z = a + bi has a real part a and an imaginary part b, where i² = −1. Addition, subtraction and multiplication work in rectangular form; division multiplies top and bottom by the conjugate of the divisor. Powers and roots use polar form, z = r(cos θ + i sin θ): De Moivre's formula raises the modulus r to the power n and multiplies the angle θ by n.
Electrical engineers use complex numbers for AC impedance and phasors, and algebra students meet them as roots of polynomials. The default multiplies (3 + 4i)(1 − 2i) = 3 − 6i + 4i − 8i² = 11 − 2i, whose modulus is √125 ≈ 11.1803.
Inputs can be rectangular (3 + 4i, with j accepted for i) or polar (2∠90). Angles follow the degree, radian or gradian setting, and the argument is given between −180° and 180°. The Argand diagram draws each number as an arrow from the origin.
جانچ کا ماخذ: 3 − 6i + 4i − 8i² = 11 − 2i (hand calculation; Python (3+4j)*(1-2j))
جانچ کا ماخذ: Python (3+4j)/(1-2j) = (-1+2j)
جانچ کا ماخذ: Python decimal: atan2(4, 3) in degrees via Machin-series arctangent (hp.py)
جانچ کا ماخذ: Python (1+1j)**8 = (16+0j); (√2)⁸ = 16 at angle 8 × 45° = 360°
Expand the brackets and replace i² with −1: (a + bi)(c + di) = (ac − bd) + (ad + bc)i. For (3 + 4i)(1 − 2i) that is (3 + 8) + (−6 + 4)i = 11 − 2i. In polar form the rule is shorter: multiply the moduli and add the angles, so 5∠53.13° × 2.236∠−63.43° = 11.18∠−10.30°.
Multiply the top and bottom by the conjugate of the divisor, which makes the denominator a real number. (3 + 4i)/(1 − 2i) = (3 + 4i)(1 + 2i)/(1² + 2²) = (3 + 6i + 4i + 8i²)/5 = (−5 + 10i)/5 = −1 + 2i. Division by 0 + 0i is undefined.
The modulus is r = √(a² + b²) and the argument is θ = atan2(b, a), which picks the correct quadrant. For 3 + 4i, r = √(9 + 16) = 5 and θ ≈ 53.130°, so 3 + 4i = 5∠53.130°. Plain arctan(b/a) gives the wrong angle when the real part is negative: −3 − 4i has an argument of about −126.870°, not 53.130°.
For z = r(cos θ + i sin θ) and a whole number n, zⁿ = rⁿ(cos nθ + i sin nθ). So (1 + i)⁸, with r = √2 and θ = 45°, equals (√2)⁸ = 16 at an angle of 8 × 45° = 360°, which is the real number 16. The same idea gives n evenly spaced nth roots: the cube roots of 8 are 2 and −1 ± 1.732051i, 120° apart.
The imaginary unit i, defined by i² = −1; −i is the other square root. Every negative number has two imaginary square roots, so √−4 = ±2i, and the principal root, the one with argument 90°, is 2i. Powers of i repeat every four steps: i, −1, −i, 1, then i again.
درستی آپ کی درج کردہ قدروں اور طریقے کے مفروضوں پر منحصر ہے۔ اعشاری حساب 50 بامعنی ہندسے استعمال کرتا ہے، مگر تخمینے، عددی طریقے اور ماخذ کا ڈیٹا کم درست ہو سکتے ہیں؛ دکھائی گئی قدروں کو راؤنڈ کرنے سے یہ حدود ختم نہیں ہوتیں۔ آزاد ذرائع کی حل شدہ مثالوں سے جانچ: 7۔ مثلاً، “(3 + 4i)(1 − 2i)” کو 3 − 6i + 4i − 8i² = 11 − 2i (hand calculation; Python (3+4j)*(1-2j)) سے جانچا جاتا ہے۔
Wolfram MathWorld — Complex Number; Wolfram MathWorld — de Moivre's Identity.
اس کیلکولیٹر میں آزاد ذرائع سے حاصل کردہ جوابات والی 7 حل شدہ مثالیں شامل ہیں۔ یہ ٹیسٹ مجموعے میں چلتی ہیں اور آپ انہیں یہاں بھی چلا سکتے ہیں۔
مربعی فارمولے سے ax² + bx + c = 0 حل کریں: اصم یا مختلط اعداد کی صورت میں عین درست جذر، ممیز، راس، محورِ تماثل اور گراف۔
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