Evaluate
45+20i
Real Part
45
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5i\times 4+5\left(-9\right)i^{2}
Multiply 5i times 4-9i.
5i\times 4+5\left(-9\right)\left(-1\right)
By definition, i^{2} is -1.
45+20i
Do the multiplications. Reorder the terms.
Re(5i\times 4+5\left(-9\right)i^{2})
Multiply 5i times 4-9i.
Re(5i\times 4+5\left(-9\right)\left(-1\right))
By definition, i^{2} is -1.
Re(45+20i)
Do the multiplications in 5i\times 4+5\left(-9\right)\left(-1\right). Reorder the terms.
45
The real part of 45+20i is 45.
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