Evaluate
15+18i
Real Part
15
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3i\times 6+3\left(-5\right)i^{2}
Multiply 3i times 6-5i.
3i\times 6+3\left(-5\right)\left(-1\right)
By definition, i^{2} is -1.
15+18i
Do the multiplications. Reorder the terms.
Re(3i\times 6+3\left(-5\right)i^{2})
Multiply 3i times 6-5i.
Re(3i\times 6+3\left(-5\right)\left(-1\right))
By definition, i^{2} is -1.
Re(15+18i)
Do the multiplications in 3i\times 6+3\left(-5\right)\left(-1\right). Reorder the terms.
15
The real part of 15+18i is 15.
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