## ksaimouli 4 years ago find intersection in terms of y of y^2-4x=4and 4x-y=16

1. ksaimouli

$y^2-4x=4 and 4x-y=16$

2. ksaimouli

@ZeHanz

3. Hero

Hint: y = 4x - 16

4. ksaimouli

i did but i dont know whre i was wrong

5. ksaimouli

i know dude to solve for x and set it eual and then solve for x

6. ksaimouli

|dw:1357491125167:dw|

7. ksaimouli

|dw:1357491191134:dw|

8. Hero

Don't make it complicated bro

9. ksaimouli

|dw:1357491240591:dw|

10. ksaimouli

solve for y am i right this is to find area between curve sooo i must to with respect y

11. Hero

Actually, that's a good approach after all.

12. ksaimouli

but something is wrong in solving hmm i am not getting the answer

13. ksaimouli

multiply both sides by 4

14. Hero

What did you get for the answer?

15. ksaimouli

.08 and -12.08

16. Hero

That's what you got for y values?

17. ksaimouli

nope

18. ksaimouli

i gote it 5 and -4

19. Hero

Okay, so what's the problem?

20. ksaimouli

arithmetic mistake lol

21. ksaimouli

now i have to integrate thats it

22. ksaimouli

|dw:1357491558149:dw|

23. ksaimouli

but not sure which one goes top and which goes bottom with respect to y

24. Hero

Here's another way to do it to avoid confusion: $\frac{y^2 - 4}{4} - \frac{16 + y}{4} = 0$

25. ksaimouli

ya i tried that worked well

26. Hero

Bro, a is always the lowest value. b is always the highest value.

27. ksaimouli

i mean the function not the points (curves)

28. ksaimouli

$x=\frac{ y^2-4 }{ 4 }$

29. Hero

Are you sure you're supposed to be using y values for a and b?

30. ksaimouli

or$x=\frac{ 16+y }{ 4 }$

31. ksaimouli

ya i am damn sure

32. Hero

I remember these. They can be tricky. What you do is just turn your graph sideways. And it will be the same as like when you're working with x-axis.

33. ksaimouli

if $\sqrt{y}$

34. ksaimouli

|dw:1357491948129:dw|

35. ksaimouli

?

36. ksaimouli

alright thx

37. Hero

Bro, I graphed it as $\frac{16 + x}{4}$ and $\frac{x^2 - 4}{4}$ You get the same area when integrating from a = -4 to b = -5 The only difference is you're using variable y instead of variable x

38. Hero

@ksaimouli

39. ksaimouli

ya i noticed it thx