(b+17)/(b^2 –1) – 1/(b+1) = (b-2)/(b-1)
b+17 1 b-2
—————— - ————— = —————
b2-1 b+1 b-1
We clear of fractions. Factor the denominator of
the first fraction
b+17 1 b-2
———————————— - ————— = —————
(b-1)(b+1) b+1 b-1
The LCD of these denominators is (b-1)(b+2)
Multiply each term by (b-1)(b+1)/1
(b-1)(b+1) b+17 (b-1)(b+1) 1 (b-1)(b+1) b-2
——————————·———————————— - ——————————·————— = ——————————·—————
1 (b-1)(b+1) 1 b+1 1 b-1
Now we cancel
(b-1)(b+1) b+17 (b-1)(b+1) 1 (b-1)(b+1) b-2
——————————·———————————— - ——————————·————— = ——————————·—————
1 (b-1)(b+1) 1 b+1 1 b-1
That leaves just
b+17 - (b-1) = (b+1)(b-2)
b + 17 - b + 1 = b2 - 2b + b - 2
18 = b2 - b - 2
0 = b2 - b - 20
0 = (b-5)(b+4)
Set each factor = 0
b-5 = 0 gives b = 5
b+4 = 0 gives b = -4
Edwin
AnlytcPhil@aol.com