8.5E: Direct Variation
Given that y varies directly as x and y = -6 when x = 2; find the value of y when x = 14.
k = -3 y = -42
Does this equation represent direct variation? y = -6x - 6
No
Does this equation represent direct variation? y = 2x + 3
No
Does this equation represent direct variation? y = -9x
Yes
Does this equation represent direct variation? y = 1/4x
Yes
Heather's weekly pay is directly proportional to the number of hours she works at the record store. Her pay is $174 for 24 hours of work. Find the amount of pay for 40 hours of work.
k = $7.25 $290
Given that y varies directly as x and y = 4 when x = 16; find the value of y when x = 20.
k = 1/4 y = 5
y varies directly as x. If x = 5 when y = 12 find x when y = 30.
k = 12/5 x = 12.5
If y = -7 when x = -14, write the direct variation equation and find y when x = 20.
y = 0.5x; y = 10
If y = 10 when x = 9, write the direct variation equation and find x when y = 9.
y = 10/9x; x = 8.1
If y = 8 when x = 4, write the direct variation equation and find y when x = 5.
y = 2x; y = 10
If x = -7 when y = -14, write the direct variation equation and find y when x = 20.
y = 2x; y = 40
If y = 27 when x = 6, write the direct variation equation and find x when y = 45.
y = 4.5x; x = 10