Q. Express as a complex number in simplest a+bi form:−6−7i−5−20iAnswer:
Multiply by Conjugate: To divide complex numbers, we multiply the numerator and denominator by the conjugate of the denominator. The conjugate of a complex number a+bi is a−bi. So, the conjugate of −6−7i is −6+7i.
Numerator Multiplication: Now, we multiply both the numerator and the denominator by the conjugate of the denominator: (−6−7i)×(−6+7i)(−5−20i)×(−6+7i).
Combine Like Terms (Numerator): First, we'll multiply out the numerator:(−5×−6)+(−5×7i)+(−20i×−6)+(−20i×7i).This simplifies to:(30)+(35i)+(120i)+(−140).
Denominator Multiplication: Now, we'll combine like terms in the numerator:30−140+35i+120i simplifies to:−110+155i.
Combine Like Terms (Denominator): Next, we'll multiply out the denominator:(−6×−6)+(−6×7i)+(−7i×−6)+(−7i×7i).This simplifies to:(36)−(42i)+(42i)−(49).
Final Complex Number: Now, we'll combine like terms in the denominator:36−49−42i+42i simplifies to:−13, since the imaginary parts cancel each other out.
Simplify Real and Imaginary Parts: We now have the complex number in the form of (−110+155i)/−13. To simplify, we divide both the real part and the imaginary part by −13: (−110/−13)+(155i/−13).
Round or Express as Fraction: Simplifying both parts gives us: 8.46153846154−11.9230769231i. However, we should round to a reasonable number of decimal places or write as a fraction if possible.
Round or Express as Fraction: Simplifying both parts gives us: 8.46153846154−11.9230769231i. However, we should round to a reasonable number of decimal places or write as a fraction if possible.Rounding to two decimal places, we get: 8.46−11.92i. Alternatively, we can express the fractions in their simplest form: (110/13)−(155/13)i.
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