Evaluate
72-54i
Real Part
72
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9\times 7+9i-9i\times 7-9i^{2}
Multiply complex numbers 9-9i and 7+i like you multiply binomials.
9\times 7+9i-9i\times 7-9\left(-1\right)
By definition, i^{2} is -1.
63+9i-63i+9
Do the multiplications.
63+9+\left(9-63\right)i
Combine the real and imaginary parts.
72-54i
Do the additions.
Re(9\times 7+9i-9i\times 7-9i^{2})
Multiply complex numbers 9-9i and 7+i like you multiply binomials.
Re(9\times 7+9i-9i\times 7-9\left(-1\right))
By definition, i^{2} is -1.
Re(63+9i-63i+9)
Do the multiplications in 9\times 7+9i-9i\times 7-9\left(-1\right).
Re(63+9+\left(9-63\right)i)
Combine the real and imaginary parts in 63+9i-63i+9.
Re(72-54i)
Do the additions in 63+9+\left(9-63\right)i.
72
The real part of 72-54i is 72.
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