+769 I need help on algebra
Find the number of ordered pairs $(a,b)$ of integers such that
\frac{a + 2}{a + 1} = \frac{b}{3}.
+129895 (a + 2) / ( a + 1) = b /3 cross-multiply
3(a + 2) = b (a + 1)
3a + 6 = ab + b
3a - ab - 1b + 6 = 0 multiply the coefficients on a,b = (3)(-1) = -3 and add to both sides
3a - ab -1b + 6 - 3 = -3
3a - ab - 1b + 3 = -3
(-a -1)(b -3) = -3
- (a + 1) ( b -3) = -3
(a + 1) ( b -3) = 3
a b
0 6
2 4
-2 0
-4 2
