a) `\frac{A}{m - 3} = \frac{m - 2}{3 -m}` ( `m \ne 3`)
`\to \frac{A}{m - 3} = \frac{2-m}{m-3}`
`\to A = 2 -m`
b) `\frac{A}{-x} = \frac{8-x^3}{x( x^2 + 2x + 4 )}` (`x \ne 0`)
`\to \frac{A}{x} = \frac{x^3 - 8}{x( x^2 + 2x + 4 )}`
`\to \frac{A}{x} = \frac{(x - 2 )( x^2 + 2x + 4 )}{x( x^2 + 2x + 4 )}`
`\to \frac{A}{x} = \frac{x - 2}{x}`
`\to A = x - 2`