Suppose that x is directly proportional to y. Let x1,x2 be two values of x such that x1/x2=4. Let their corresponding y values be y1,y2, respectively. If at least one of y1,y2 is nonzero, find y2/y1.
+23246 x is directly proportional to y ---> y = k·x ---> y1 = k·x1 ---> y2 = k·x2
y1 = k·x1 ---> k = y1 / x1
y2 = k·x2 ---> k = y2 / x2
Combining: y1 / x1 = y2 / x2
Multiplying both sides by (x1 / y2) ---> (x1 / y2) · (y1 / x1) = (x1 / y2) · (y2 / x2)
---> y1 / y2 = x1 / x2
Since x1 / x2 = 4 ---> y1 / y2 = 4
Therefore ---> y2 / y1 = 1/4
+23246 x is directly proportional to y ---> y = k·x ---> y1 = k·x1 ---> y2 = k·x2
y1 = k·x1 ---> k = y1 / x1
y2 = k·x2 ---> k = y2 / x2
Combining: y1 / x1 = y2 / x2
Multiplying both sides by (x1 / y2) ---> (x1 / y2) · (y1 / x1) = (x1 / y2) · (y2 / x2)
---> y1 / y2 = x1 / x2
Since x1 / x2 = 4 ---> y1 / y2 = 4
Therefore ---> y2 / y1 = 1/4
