y=3x is a direct variation in that y varies directly with x by a factor of 3. Any linear equation (a polynomial of degree 1, which is a polynomial equation with a highest exponent of 1), is a direct variation of y to x by some constant, and this constant is simply the coefficient of the "x" term. Other examples: y=(1/2)x is a direct variation, and the constant of variation is 1/2 y=-9x is a direct variation, and the constant of variation is -9
find the direct variation equation 3x+y=0
No, it is not a direct variation.
The question is not clear. But if you want this in the form y=kx, then k must be 1.5
No, this is an inverse variation.