Alternatively, you can factor out i^2 from the equation to get i^2 (3 + i − i^2 ).
Next substitute −1 for i^2 in the new equation: −1(3 + i −(−1)) = −1(3 + i + 1) =
−1(4 + i). Then distribute −1: −4 − i.
21 . B
Get a common denominator on the left side:
Cross multiply: 13 − 2d = 17, so −2d = 4, and d = −2.
22 . E
Use the Pythagorean theorem: