## kevincourtes 2 years ago Need help with this problem...

1. kevincourtes

2. kausarsalley
3. cwrw238

if y varies directly with x then y = kx where k is a constant find k by plugging in the given values of y and x when y = 3 , x = 2 3 = k * 2 can you find k?

4. kevincourtes

@cwrw238 3/2?

5. cwrw238

divide both sides of the equation by 2 to find k right

6. kevincourtes

@cwrw238 so the answers D right?

7. cwrw238

so now we have |dw:1366501494754:dw|

8. kevincourtes

@cwrw238 can you help me with this one?

9. cwrw238

can u see what i've done i've substituted 3/2 for k now to find y when x = 3 plug in 3 for x and work out the value of y

10. kevincourtes

@cwrw238 9/2?

11. cwrw238

right

12. cwrw238

if y varies directly by x y = kx and k = y/x

13. kevincourtes

@cwrw238 i dont understand the 2nd problem

14. cwrw238

now plug in the values of x and y y = -3 and x = 1 k = -3 / 1 = -3 y = -9 and x = 3 k = -9/3 = -3 also k = -15 / 5 = -3 so is this varying direct;y?

15. kevincourtes

@cwrw238 no?

16. cwrw238

these values of y and x do satisfy the relation y = kx which is direct variation do you see that?

17. cwrw238

k - -3 in all 3 cases

18. kevincourtes

@cwrw238 ohhhh okay so the answer would be A?

19. cwrw238

right there are 2 types of variation direct where y = kx and indirect where y = k / x

20. kevincourtes

@cwrw238 thanks

21. kevincourtes

@cwrw238 also can you help me with this last one?