Solve 7i(2+6i)

$$7 i ( 2 + 6 i )$$

Evaluate

$$-42+14i$$

Solution Steps

Multiply 7i times 2+6i.

$$7i\times 2+7\times 6i^{2}$$

By definition, i^{2} is -1.

$$7i\times 2+7\times 6\left(-1\right)$$

Do the multiplications. Reorder the terms.

$$-42+14i$$

Real Part

$$-42$$

Solution Steps

Multiply 7i times 2+6i.

$$Re(7i\times 2+7\times 6i^{2})$$

By definition, i^{2} is -1.

$$Re(7i\times 2+7\times 6\left(-1\right))$$

Do the multiplications in 7i\times 2+7\times 6\left(-1\right). Reorder the terms.

$$Re(-42+14i)$$

The real part of -42+14i is -42.

$$-42$$