Work Step by Step
Using the rules of complex numbers and combining like terms: $$\left(2-7i\right)\left(1+2i\right) \\ \left(2\cdot \:1-\left(-7\right)\cdot \:2\right)+\left(2\cdot \:2+\left(-7\right)\cdot \:1\right)i \\ 16-3i$$
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