Which expression represents the partial fraction decomposition of 1x2+3x+2\frac{1}{x^2+3x+2}x2+3x+21?
1x+1−1x+2\frac{1}{x+1} - \frac{1}{x+2}x+11−x+21
1x+2−1x+1\frac{1}{x+2} - \frac{1}{x+1}x+21−x+11
1x+1+1x+2\frac{1}{x+1} + \frac{1}{x+2}x+11+x+21
2x+1−1x+2\frac{2}{x+1} - \frac{1}{x+2}x+12−x+21