Question

Which equation describes a relationship that is directly proportional? y=9 y=3x y=15 y=x+4

Answer 1

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Step-by-step explanation:

Step-by-step explanation:

Directly proportional relation is one in which the value of x and y gets increases or decreased in same proportion.

example of such relation can be y = kx

where k is the constant of proportionality which depicts by how much value of y will change in response to change of x.

now in the option

A and B

y= 9 , y =1/5

value of y is constant and does not depend on other variable. it value will remain same.

for y = x+4

value of y increases with x but it does not increase proportionally.

let see an example for x =1 , y = 1+4 = 5

x =2 , y = 2+4 = 6

(1,5) and (2,6) are not proportionally changing also this equation is not of form y = kx

thus, it is incorrect option.

(C) y = 3x

here equation is form y =kx . in place of k there is 3