MATH 110 Lecture 10: MATH 110 lecture 10
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Math 110 lecture 10 inverse proportion. Direct proportion looks like this: y = kx if x increases, then y increases proportionally. Inverse proportion looks like this: xy = k if x increases, then y decreases proportionally. If k is a non-zero constant and x doubles, then y is halved: let constant k = 20, x = 5. Find y: is x doubles to 10? y = 20. 2 is half of the original y-value of 4. There are 4 variables: x1, x2, y2, y1 x1y1 = k and x2y2 = k. And k is the same in each case, then: x1y1 = x2y2. That is: y2 = x1y1 x2 if x1y1 is a constant, then as x2 increases, y2 decreases. Driver 1 drives for 24 mins 30 sec at 120 mph. Driver 2 drives for 23 mins 45 sec at x mph. Find x: t1 = 24 mins 30 sec, s1 = 120 mph, t2 = 23 mins 45 sec.
