Q. Express as a complex number in simplest a+bi form:−1+i−2+5iAnswer:
Multiply by Conjugate: Multiply the numerator and denominator by the conjugate of the denominator to eliminate the imaginary unit i from the denominator.The conjugate of (−1+i) is (−1−i).−1+i−2+5i⋅−1−i−1−i
Apply Distributive Property: Apply the distributive property (foil method) to multiply out the numerators and denominators.Numerator: (−2+5i)×(−1−i)=(−2)(−1)+(−2)(−i)+(5i)(−1)+(5i)(−i)Denominator: (−1+i)×(−1−i)=(−1)(−1)+(−1)(−i)+(i)(−1)+(i)(−i)
Perform Multiplication: Perform the multiplication for both the numerator and the denominator.Numerator: 2+2i−5i−5i2Since i2=−1, replace i2 with −1.Numerator: 2+2i−5i+5Denominator: 1−i+i−i2Similarly, replace i2 with −1 in the denominator.Denominator: 1+1
Combine Like Terms: Combine like terms in both the numerator and the denominator.Numerator: (2+5)+(2i−5i)Numerator: 7−3iDenominator: 1+1Denominator: 2
Divide to Get Complex Number: Divide the numerator by the denominator to get the complex number in a+bi form.(7−3i)/2a=27b=−23So the complex number in a+bi form is 27−23i.
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