Evaluate
-18-21i
Real Part
-18
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7\times \left(-3i\right)-6\left(-3\right)i^{2}
Multiply 7-6i times -3i.
7\times \left(-3i\right)-6\left(-3\right)\left(-1\right)
By definition, i^{2} is -1.
-18-21i
Do the multiplications. Reorder the terms.
Re(7\times \left(-3i\right)-6\left(-3\right)i^{2})
Multiply 7-6i times -3i.
Re(7\times \left(-3i\right)-6\left(-3\right)\left(-1\right))
By definition, i^{2} is -1.
Re(-18-21i)
Do the multiplications in 7\times \left(-3i\right)-6\left(-3\right)\left(-1\right). Reorder the terms.
-18
The real part of -18-21i is -18.
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