Suppose y varies directly with x, and y = 10 when x = –3. What direct variation equation relates x and y? What is the value of y when x = –1?
(1 point)
a. y = –3 over 10x;3 over 10
b. y = 1 over 10x; –3 over 10
c. y = 10 over 3x; –10 over 3
d. y = –10 over 3x; 10 over 3
To find the direct variation equation, we can use the formula y = kx, where k is the constant of variation.
We are given that y = 10 when x = -3. Plugging these values into the equation, we get 10 = k(-3).
Solving for k, we divide both sides by -3 to get k = -10/3.
Therefore, the direct variation equation is y = (-10/3)x.
To find the value of y when x = -1, we can plug x = -1 into the equation:
y = (-10/3)(-1) = 10/3.
Therefore, the value of y when x = -1 is 10/3.
The correct answer is d. y = -10/3x; 10/3.