Accedmychevron_right11thchevron_rightmathchevron_rightComplex Numberschevron_rightExercise 1.1

(iii) i1+i\frac{i}{1 + i}

Solution

Multiply numerator and denominator by conjugate (1i):i1+i1i1i=i(1i)(1+i)(1i)Simplify numerator:i(1i)=ii2=i(1)=1+iSimplify denominator:(1+i)(1i)=12+12=2Write in a+ib form:1+i2=12+12i\begin{aligned} & \boxed{\text{Multiply numerator and denominator by conjugate } (1-i):} \\ \\ & \frac{i}{1+i} \cdot \frac{1-i}{1-i} = \frac{i(1-i)}{(1+i)(1-i)} \\ \\ & \boxed{\text{Simplify numerator:}} \\ \\ & i(1-i)=i-i^2=i-(-1)=1+i \\ \\ & \boxed{\text{Simplify denominator:}} \\ \\ & (1+i)(1-i)=1^2+1^2=2 \\ \\ & \boxed{\text{Write in } a+ib \text{ form:}} \\ \\ & \frac{1+i}{2} = \frac{1}{2} + \frac{1}{2}i \end{aligned}