+422 Suppose that a is inversely proportional to b. If a=4 when b=9, find a when b=-72.
+129849 We have that
b = k/a so
9 = k/ 4 multiply both sides by 4
36 = k
And when b = -72 we have that
-72 = 36 / a multiply both sides by a, divide both sides by -72
a = 36 / -72 = - 1 / 2
Note one thing...in inverse proportions....the product of ab is a constant value
So
ab = ab
4*9 = (-1/2)(-72)
36 = 36
