SOLUTION: For the following problems, y varies directly with x If y is -3 when x is 5, find y when x is -10.

Click here to see ALL problems on Functions

Question 35507This question is from textbook
: For the following problems, y varies directly with x
If y is -3 when x is 5, find y when x is -10. This question is from textbook

Found 3 solutions by narayaba, Nate, Prithwis:
Answer by narayaba(40)   (Show Source):
You can put this solution on YOUR website!
y varies directly with x
y = c*x, where c is proportionality constant.
y = -3 when x = 5
-3 = c*5
c = -3/5
y = (-3/5)*x
x = -10, y =(-3/5)*(-10) = 6

Answer by Nate(3500)   (Show Source):
You can put this solution on YOUR website!
y/x=y/x
(-3)/(5)=y/(-10)
6=y

Answer by Prithwis(166)   (Show Source):
You can put this solution on YOUR website!
y varies directly with x => y = kx;
y = -3 and x=5
=> -3 = 5k
=> k = -3/5;
So, y = (-3/5)x;
If x = -10, y = (-3/5)(-10) = 6
Answer: y = 6