Accedmychevron_right11thchevron_rightmathchevron_rightPartial Fractionschevron_rightExercise 5.1

Solution

(x1)(x2)(x3)(x4)(x5)(x6)\frac{(x-1)(x-2)(x-3)}{(x-4)(x-5)(x-6)}

Since degrees are equal, divide first.

(x1)(x2)(x3)(x4)(x5)(x6)=1+R(x)(x4)(x5)(x6)\frac{(x-1)(x-2)(x-3)}{(x-4)(x-5)(x-6)}=1+\frac{R(x)}{(x-4)(x-5)(x-6)}

Now let:

(x1)(x2)(x3)(x4)(x5)(x6)=1+Ax4+Bx5+Cx6\frac{(x-1)(x-2)(x-3)}{(x-4)(x-5)(x-6)}=1+\frac{A}{x-4}+\frac{B}{x-5}+\frac{C}{x-6}

Solving gives A=3A=3, B=24B=-24, C=30C=30.

(x1)(x2)(x3)(x4)(x5)(x6)=1+3x424x5+30x6\boxed{\frac{(x-1)(x-2)(x-3)}{(x-4)(x-5)(x-6)}=1+\frac{3}{x-4}-\frac{24}{x-5}+\frac{30}{x-6}}