Evaluate
4+20i
Real Part
4
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5\times \left(4i\right)-4i^{2}
Multiply 5-i times 4i.
5\times \left(4i\right)-4\left(-1\right)
By definition, i^{2} is -1.
4+20i
Do the multiplications. Reorder the terms.
Re(5\times \left(4i\right)-4i^{2})
Multiply 5-i times 4i.
Re(5\times \left(4i\right)-4\left(-1\right))
By definition, i^{2} is -1.
Re(4+20i)
Do the multiplications in 5\times \left(4i\right)-4\left(-1\right). Reorder the terms.
4
The real part of 4+20i is 4.
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