Is 3y=9x a direct variation and if so, what is the constant?

2 Answers
Apr 13, 2018

k=3k=3

Explanation:

"a direct variation equation has the form"a direct variation equation has the form

•color(white)(x)y=kxlarrcolor(blue)"k is the constant of variation"xy=kxk is the constant of variation

3y=9xlarrcolor(blue)"divide both sides by 3"3y=9xdivide both sides by 3

rArry=3xy=3x

"this is a direct variation equation with "k=3this is a direct variation equation with k=3

Apr 13, 2018

Yes, it is. And constant is 3. See below

Explanation:

3y=9x3y=9x is a direct variation because for two diferente values values of xx, lets say x_0x0 and x_1x1 we have

3y_0=9x_03y0=9x0 and 3y_1=9x_13y1=9x1 substracting both we have

3y_0-3y_1=9x_0-9x_13y03y1=9x09x1

3(y_0-y_1)=9(x_0-x_1)3(y0y1)=9(x0x1) from here we have

(y_0-y_1)/(x_0-x_1)=9/3=3y0y1x0x1=93=3