Question

how to understand whether direct variation is there aur inverse variation in a question​ sorry by mistake I have selected the subject as English it's actually maths

Answer 1

Directly proportional or variation is a proportionality where a certain number multiplies by a certain number.

• examples of directly proportional are density and mass because if density increases then mass increases continuously.

• velocity and distance

• voltage, resistance and current are all directly proportional

Inversely proportional or variation is a proportionality where a certain number gets divided by a certain number.

• examples of inversely proportional are density and volume because if density increases then volume decreases exponentially

• velocity and time ( if time increases then velocity decreases)

If you want to find whether direct variation or inverse variation in a question, take out the formula first.

For ex : d = m/v ( density = mass/volume)

Now insert some random values into the formula.To find the relation between density and mass. keep the volume constant.

For ex ; d = 5kg/L; m = 20kg; v = 4L

let m = 24kg = 24/4 = density = 6kg/L and so on.....

d  (kg/L)                      m(kg)

5                                       20

6                                        24

7                                         28

You can observe that as mass increases, density also increases exponentially. Therefore, they are directly proportional

Likewise, if you want to know the relation b/w density and volume. Plug in some random values and keep mass value constant.

For ex ; d = 20kg/L; m = 20kg; v = 1L

d(kg/L)                   v(L)

     20                       1

      10                       2

       5                        4

You can observe that as volume increases, density decreases exponentially. Therefore, they are inversely proportional.

Hope it is super-clear! ^_^