Question

Сведите дробь 6/(b-4) к знаменателю:
1) 5b-20;
2) 12-3b;
3) b²-4b;

Answer 1

$1) \frac{6}{b-4}=\frac{6\cdot 5}{(b-4) \cdot 5)}=\frac{30}{5b-20};\\ 2) \frac{6}{b-4}=-\frac{6}{4-b}=-\frac{6 \cdot 3}{(4-b) \cdot 3}=-\frac{18}{12-3b}; \\ 3) \frac{6}{b-4}=\frac{6 \cdot b}{(b-4) \cdot b}=\frac{6b}{b^2-4b}$