Evaluate
13+18i
Real Part
13
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4\times 2+4\times \left(5i\right)-i\times 2-5i^{2}
Multiply complex numbers 4-i and 2+5i like you multiply binomials.
4\times 2+4\times \left(5i\right)-i\times 2-5\left(-1\right)
By definition, i^{2} is -1.
8+20i-2i+5
Do the multiplications.
8+5+\left(20-2\right)i
Combine the real and imaginary parts.
13+18i
Do the additions.
Re(4\times 2+4\times \left(5i\right)-i\times 2-5i^{2})
Multiply complex numbers 4-i and 2+5i like you multiply binomials.
Re(4\times 2+4\times \left(5i\right)-i\times 2-5\left(-1\right))
By definition, i^{2} is -1.
Re(8+20i-2i+5)
Do the multiplications in 4\times 2+4\times \left(5i\right)-i\times 2-5\left(-1\right).
Re(8+5+\left(20-2\right)i)
Combine the real and imaginary parts in 8+20i-2i+5.
Re(13+18i)
Do the additions in 8+5+\left(20-2\right)i.
13
The real part of 13+18i is 13.
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