Evaluate
-21+24i
Real Part
-21
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-8\times \left(-3i\right)-7\left(-3\right)i^{2}
Multiply -8-7i times -3i.
-8\times \left(-3i\right)-7\left(-3\right)\left(-1\right)
By definition, i^{2} is -1.
-21+24i
Do the multiplications. Reorder the terms.
Re(-8\times \left(-3i\right)-7\left(-3\right)i^{2})
Multiply -8-7i times -3i.
Re(-8\times \left(-3i\right)-7\left(-3\right)\left(-1\right))
By definition, i^{2} is -1.
Re(-21+24i)
Do the multiplications in -8\times \left(-3i\right)-7\left(-3\right)\left(-1\right). Reorder the terms.
-21
The real part of -21+24i is -21.
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