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Inverse Variation

While straight variation describes a linear relationship between two variables , inverse variation describes some other kind of relationship.

For ii quantities with inverse variation, as one quantity increases, the other quantity decreases.

For case, when you lot travel to a detail location, as your speed increases, the fourth dimension it takes to get in at that location decreases. When you decrease your speed, the time it takes to arrive at that location increases. So, the quantities are inversely proportional.

An inverse variation can be represented by the equation x y = k or y = thou x .

That is, y varies inversely as ten if in that location is some nonzero constant k such that, 10 y = 1000 or y = g x where ten 0 , y 0 .

Suppose y varies inversely equally x such that 10 y = 3 or y = iii 10 . That graph of this equation shown.

Since chiliad is a positive value, every bit the values of x increase, the values of y subtract.

Annotation: For direct variation equations, y'all say that y varies directly as x . For inverse variation equations, you say that y varies inversely as 10 .

Production Rule for Inverse Variation

If ( x 1 , y i ) and ( x 2 , y 2 ) are solutions of an inverse variation, then x one y 1 = 1000 and x ii y 2 = k .

Substitute 10 one y 1 for k .

x 1 y 1 = x 2 y two or x 1 10 two = y two y i

The equation x i y 1 = 10 2 y 2 is chosen the product rule for inverse variations.

Instance:

In a manufactory, 10 men can do the job in 30 days. How many days it will have if 20 men do the same job?

Hither, when the human being ability increases, they will need less than 30 days to complete the aforementioned job. And then, this is an changed variation.

Let x be the number of men workers and let y exist the number of days to consummate the piece of work.

And then, x 1 = 10 , ten 2 = 20 and y ane = 30 .

By the product rule of changed variation,

( 10 ) ( xxx ) = ( xx ) ( y 2 ) 300 = 20 y 2

Solve for y 2 .

y 2 = 300 20 = fifteen

Therefore, 20 men can practice the same job in 15 days.