Question

Does the equation represent a direct variation? If so, find the constant of variation.

5x = -3y

Answer 1

A. no
B. yes; k = -5/3
C. yes; k = 5/3
D. yes; k = 3/5
choices

Answer 2

Yes,
can write as
-3y = 5x
y = (-5/3) *x

the constant of variation is -5/3

Answer 3

Suppose y varies directly with x, and y = 8 when x = –6. What direct variation equation relates x and y? What is the value of y when x = –2?

Answer 4

A. y = –0.75x; 1.50
B. y = –1.33x; 2.67
C. y = 1.33x; –2.67
D. y = 0.13x; –0.25
choices

Answer 5

so the answer is B

B. y = –1.33x; 2.67

Answer 6

Y=bx
when x = -6

y=b*-6

but we are given that when b =-6, y =8

Therfore rewrite:

y=B*(-6)

as

8 = b*(-6)

=> b = -8/6

Therfore the equation is

y= (-8/6)*x = -1.333x
y= -1.333x


b) when x=-2

just substitute x =-2 in the above equation:

y= -1.333x , plug in -2 for x
y= -1.33 * (-2) = 2.666 ( multiplying two negative signs turns to a positive sign)
=> y= 2.666 rounded to 2.67




so the answer is B

B. y = –1.33x; 2.67