Question

Выражение b+2/b^2+3b - 1+b/b^2-9 при b=5 .с подробным решением; )

Answer 1

$\frac{b+2}{b^2+3b} - \frac{1+b}{b^2-9}= \frac{b+2}{b(b+3)} - \frac{1+b}{(b-3)(b+3)}= \frac{(b+2)(b-3)}{b(b+3)(b-3)} - \frac{b(1+b)}{b(b-3)(b+3)}= \\ =\frac{(b+2)(b-3)-b(1+b)}{b(b+3)(b-3)}=\frac{b^2-3b+2b-6-b-b^2}{b(b+3)(b-3)}=\frac{-2b-6}{b(b+3)(b-3)}= \frac{-2(b+3)}{b(b+3)(b-3)}= \\ =\frac{-2}{b(b-3)}=\frac{-2}{5(5-3)}=- \frac{1}{5}$

Answer 2

5+2/5^2+3*5 -- 1+5/5^2-9=7/40 -- 6/16= 0,175-0,375= -0,2